Buy the Altor ICON if the trailer behind it is worth real money. It is the only lock here designed around the attack that actually defeats coupler locks — a cordless angle grinder — rather than around prying and picking, and it comes in a variant matched to your coupler’s latch design instead of a shape that approximately fits everything.
For an adjustable design, consider the Fastway Fortress. Fastway lists compatibility with virtually all 1-7/8, 2 and 2-5/16 inch couplers. That reduces variant selection, but you still need to confirm the body and shackle seat and lock on your actual coupler.
And if what you are protecting is the ball mount rather than the trailer, that is a different product entirely — a BOLT receiver lock, which opens with your tow vehicle’s own ignition key.
Before any of that, two things decide whether the lock you order is the right one, and neither is the one every roundup leads with.
Quick picks
Best overall
Altor ICON
Built against the attack that actually defeats coupler locks — the angle grinder — with a disc cylinder and a variant for each OEM latch design.
Best adjustable fit
Fastway Fortress
One adjustable body covers three common ball sizes; confirm it seats and locks on your actual coupler.
Best US-made
Proven 2516
The widest range of coupler-specific variants and a published fitment index — provided you pay to upgrade the standard cylinder.
Best close fit
AMPLock BRP-2516
Moulded to a straight-lip coupler rather than clamped over it, which leaves no gap for a pry bar. Straight-lip couplers only.
Best hitch pin lock
BOLT Receiver Lock
Uses a compatible vehicle key, reducing the number of separate keys to carry.
How the six compare
| Model | Type | Fits | Cylinder | Material | Warranty | Price | Buy |
|---|---|---|---|---|---|---|---|
| Altor ICON | Coupler lock | 2 in and 2-5/16 in | Disc detainer, described by Altor as pick resistant | Hardened cast steel with radial fin geometry | Limited lifetime | $$$$$ | Check price(opens in a new tab) |
| Proven 2516 | Coupler lock | 2-5/16 in | 7-pin tubular (Cobra) as standard. Proven disc detainer, Medeco M3 and Abloy cylinders are paid upgrades, not the default | Billet 6061 aluminium or solid 303 stainless steel, depending on option | Not published on the product page | $$$$ | Check price(opens in a new tab) |
| AMPLock BRP-2516 | Coupler lock | 2-5/16 in only — the 2 in version is the separate BRP-2 | Disc cylinder with a rotating face intended to resist drilling | Ductile iron and stainless steel | 5 years with registration | $$$$ | Check price(opens in a new tab) |
| Fastway Fortress | Coupler lock | 1-7/8 in, 2 in and 2-5/16 in | Cylinder and key with barrel-style keys, per Fastway. Not a disc detainer, despite claims to that effect on some roundups | Alloy steel with a corrosion-resistant finish | Limited lifetime | $$ | Check price(opens in a new tab) |
| BOLT Receiver Lock | Receiver / hitch pin lock | — | Plate tumbler with a sidebar, stated to resist picking and bumping | Stainless steel pin | Limited lifetime, covering mechanical failure during vehicle ownership | $ | Check price(opens in a new tab) |
| PACLOCK 80-Series | Receiver / hitch pin lock | — | Three grades offered — UCS, standard rekeyable, and high-security rotating disc | High yield strength stainless steel pin; 6061 aluminium body, anodised or 304 stainless | Not published on the 80-series product pages | $$$ | Check price(opens in a new tab) |
Match the lock to the connection
A receiver pin, a coupler latch and an empty ball socket are different places to secure. The last two products in this comparison are receiver locks; the first four are storage coupler locks.
Follow the connection from the tow vehicle to the trailer. These simplified side views show lock locations, not a complete towing setup or a guarantee against theft.
Hitched and parked
- Receiver lock: retains the ball mount in the vehicle’s receiver.
- Latch-pin lock: secures a compatible coupler’s latch. It is a separate location and fit check.
A receiver lock alone leaves the coupler latch independent. Choose latch hardware permitted by the coupler maker and retain all required towing safety devices.
Unhitched and stored
Coupler storage lock: fills or encloses the socket to obstruct normal coupling. Match the ball size, coupler shape and lock-maker fitment instructions.
Remove it before hitching. A latch-pin lock may also be useful, but locking an empty coupler’s latch is not the same as filling or enclosing its socket.
Each lock covers one connection. No single lock secures every removable hitch part or prevents every way of moving a trailer. Use locks as part of a storage plan.
Location examples: BOLT’s receiver, coupler-pin and storage coupler locks, and the Fastway Fortress storage lock. Exact designs vary; confirm pin diameter, usable span and coupler compatibility.
Unhitched storage: a correctly fitted coupler lock obstructs normal coupling to the trailer. A receiver lock left on the tow vehicle does not protect the unhitched trailer.
Hitched and parked: a receiver lock helps retain the ball mount, but the coupler latch is still a separate connection. Check whether a compatible latch-pin lock is appropriate, along with any removable parts of an adjustable hitch. Do not treat either lock as securing the whole assembly by itself.
Identify your coupler before you order
Trigger latch
Squeeze handle under the head
You pull a trigger upward beneath the coupler to release it.
Thumb / lever latch
Flip-up lever on top
A flat lever lies along the top and lifts from the front.
Yoke latch
Pivoting yoke over the head
A U-shaped yoke pivots down over the ball and pins in place.
Sleeve / collar
Collar slides along the neck
A collar slides along the neck to lock the socket shut.
Work it out in two steps.
Step one: the ball size. Read the coupler marking; common US bumper-pull sizes are 1-7/8, 2 and 2-5/16 inches. Do not infer it from trailer weight. A conventional fifth-wheel hitch uses a kingpin, so it needs a different lock.
Ball size does not choose a weight-distribution system by itself. For those separate compatibility checks, see Equal-i-zer vs Blue Ox SwayPro and Andersen vs Equal-i-zer.
Step two: the latch design. Look at how the coupler locks onto the ball. A trigger you squeeze from underneath, a lever lying flat along the top, a U-shaped yoke that pivots down over the ball, or a collar that slides along the neck. That is the distinction the premium locks are built around.
Two manufacturers will do this for you rather than leaving it to guesswork. Proven Industries publishes a coupler index and will identify fitment from photographs emailed to its support address. Altor lists its variants by OEM name — Demco, Fulton, Bulldog, Dexter, Atwood, Ram, Husky — which is usually faster if you know who made your trailer.
Latch-pin locks need the correct pin diameter and usable span; enclosing locks need the model and clearance checks specified by their manufacturer. Record those details on the printable card in our coupler lock sizing guide.
Check the exact cylinder supplied
Cylinder type identifies part of the mechanism; it does not by itself establish an attack-resistance rating. We have not comparatively tested these locks. Consider the complete body, shielding and fit as well as the cylinder, and check any independent test evidence for the exact variant being sold.
- Proven’s standard cylinder is not its best one. The Model 2516 ships with a 7-pin tubular cylinder as standard. Its disc detainer, along with Medeco M3 and Abloy options, is a paid upgrade. A roundup that credits the 2516 with a disc detainer is describing a version you have to choose and pay for.
- The Fastway Fortress uses barrel-style keys, per Fastway’s own product page, not the disc detainer it is sometimes credited with. Confirm the supplied cylinder and actual coupler fit; a key shape alone is not a comparative security test.
The locks
Best overall
Altor ICON Trailer Lock for Bumper Pull Trailers
Why it's here
The ICON’s radial fin geometry is designed to increase the material a grinder must cut through. B&W reports that its own testing took over 90 minutes, several blades and several battery packs to compromise the lock. Treat this as a manufacturer claim, rather than a guaranteed delay or a comparison with every competing lock. It does not establish which attack accounts for most trailer thefts.
The current B&W ICON selector asks for ball size and coupler design. B&W states that it acquired the Altor product line. Match the exact selector entry and confirm any unlisted coupler with the maker; a fixed count of variants is not a fitment rule.
Full specifications
| Lock Type | Coupler lock |
|---|---|
| Coupler Sizes | 2 in and 2-5/16 in |
| Coupler Styles | Sold as a variant per OEM latch design — flat lip, cast, cast/sleeve lock, UFP A-60 and XR-84, yoke latch, yoke, rolled lip, cast auto-locking, and cast with twist latch |
| Cylinder Type | Disc detainer, described by Altor as pick resistant |
| Material | Hardened cast steel with radial fin geometry |
| Hardness | Not specified numerically by the manufacturer |
| Weather Protection | Weather resistance coating against water, dust and corrosion |
| Grinder Resistance | B&W now publishes the ICON test claim: over 90 minutes, multiple blades and multiple battery packs to compromise the lock — a manufacturer claim, not an independent result |
| Weight (lb) | B&W describes over 20 lb of hardened steel; confirm total weight for the selected variant |
| Country Of Origin | B&W says some components were historically sourced overseas; confirm the current variant |
| Warranty | Limited lifetime |
Specifications verified August 12, 2026 from Current B&W ICON page — acquisition, fit selector, steel-mass statement and test claim rechecked 2026-11-07; other dates unchanged .
Strengths
- Disc detainer cylinder as standard rather than as a paid upgrade
- Designed against angle grinders specifically — hardened cast steel with radial fin geometry
- Variants matched to listed OEM coupler designs; select both ball size and coupler style
- Limited lifetime warranty, and a weather coating plus internal sealing against corrosion
- B&W publishes an ICON grinder-test result; it is the manufacturer’s own test
Weaknesses
- Comfortably the most expensive lock here
- B&W describes over 20 lb of hardened steel, but does not give a numeric hardness or total weight for every variant
- The 90-minute grinder figure published by B&W is a manufacturer test, not an independent result
- Multiple variants mean the exact ball size and coupler style must be matched before ordering
- Bumper-pull couplers only — no gooseneck or fifth-wheel option in this model
Fit: Bumper-pull couplers only. The variant must match your coupler's latch design, not just its ball size — ordering by ball size alone is the most likely way to receive a lock that will not close on your coupler.
Buy it if
The trailer is worth real money and spends time parked unattended, and you can identify your coupler's latch design before ordering.
Choose something else if
You cannot confirm which ICON variant fits your coupler. Resolve fitment before ordering.
Best adjustable fit
Fastway Fortress Universal Coupler Lock
Why it's here
Fastway states broad compatibility, rather than asking you to select a separate lock for each latch design. Its wording is virtually all, not every possible coupler and accessory combination. Confirm the fit before relying on it.
Fastway specifies barrel-style keys, rather than a disc-detainer mechanism. That describes the supplied design; we have not measured its pick or cutting resistance against the other products here.
Full specifications
| Lock Type | Coupler lock |
|---|---|
| Coupler Sizes | 1-7/8 in, 2 in and 2-5/16 in |
| Coupler Styles | Universal — one body covers the three ball sizes |
| Cylinder Type | Cylinder and key with barrel-style keys, per Fastway. Not a disc detainer, despite claims to that effect on some roundups |
| Material | Alloy steel with a corrosion-resistant finish |
| Shackle | Hardened reversible U-shackle with dual locking pins |
| Weather Protection | Winged dust cover over a front-facing cylinder |
| Dimensions | 3.28 x 9.25 x 9.25 in |
| Weight (lb) | About 3 |
| Country Of Origin | Designed and engineered in the USA — manufacturing location not stated |
| Warranty | Limited lifetime |
Specifications verified August 12, 2026 from Fastway Fortress coupler lock product page — sizes, materials, key type, dimensions, warranty .
Strengths
- One adjustable body covers three common ball sizes; actual seating and closure still need checking
- Hardened reversible U-shackle with dual locking pins engaging both ends of the shackle
- Winged dust cover over a front-facing cylinder, which is the right place for it on a trailer tongue
- Limited lifetime warranty
- The only lock here at a genuinely mid-market price
Weaknesses
- Fastway specifies barrel-style keys; no comparative attack-resistance rating is established here
- About 3 lb, against 10 lb for the heavier AMPLock and considerably more for the Altor
- "Designed and Engineered in the USA" is a statement about design, not about where it is manufactured
- Covers the socket rather than closing to the coupler’s own shape, so the fit is looser than a moulded lock
Fit: Fastway states that it fits virtually all couplers in the listed sizes. No latch-specific variant is selected, but confirm that the body and shackle seat and lock as the instructions show on the actual coupler.
Buy it if
You prefer an adjustable design and can confirm it seats and locks correctly on your coupler.
Choose something else if
Its body and shackle do not seat and lock correctly on your coupler, or you need independently verified attack-resistance evidence.
Best US-made, with a caveat
Proven Industries Model 2516 Trailer Coupler Lock
Why it's here
Proven’s fitment support is the best in the category. The coupler index and the photograph service solve the exact problem that sends most coupler locks back, and the variant range — trigger and thumb latch, Atwood yoke latch, cast steel, Airstream, and a grinder-resistant version — is wider than anyone else’s.
The caveat is the cylinder, and it is worth being blunt about. The 2516 ships with a tubular cylinder as standard. Proven’s own disc detainer, and the Medeco and Abloy options above it, cost more. That is a legitimate way to sell a lock, but it means the specification a reader thinks they are buying and the one that arrives are only the same if they chose the upgrade.
On the “Proven coupler lock defeated” video you may find. A 2021 article still circulating refers to a YouTube video showing a Proven coupler lock being opened easily. We looked at it against the same standard we applied to the locks in “What we left out” below, and it does not meet it: the article names no model, no cylinder type, no attack method, no video author and no date, and links to nothing. It also reports that Proven responded by changing the construction material, the lock mechanism and the position of the spring pin holding the locking portion in place. A claim with no identifiable subject, about a design that has since changed, is not evidence we can act on — where the do-not-buy list further down names specific current models and specific failure modes. We mention it because you will find it, not because it changed our view.
Full specifications
| Lock Type | Coupler lock |
|---|---|
| Coupler Sizes | 2-5/16 in |
| Coupler Styles | Most trigger latch and thumb latch couplers. Separate models cover other designs — 2516-A for Atwood yoke latch, 2516-B2 for cast steel, 2516-AS for Airstream |
| Cylinder Type | 7-pin tubular (Cobra) as standard. Proven disc detainer, Medeco M3 and Abloy cylinders are paid upgrades, not the default |
| Material | Billet 6061 aluminium or solid 303 stainless steel, depending on option |
| Safety Chains | Secures 5/16 in safety chain hooks in most cases, not guaranteed |
| Weight (lb) | Not specified by the manufacturer |
| Country Of Origin | Majority manufactured in the USA, per Proven Industries |
| Warranty | Not published on the product page |
Specifications verified August 12, 2026 from Proven Industries Model 2516 product page — materials, cylinder options, fitment, pricing .
Strengths
- The widest set of coupler-specific variants of any brand here, plus a published coupler index
- Proven will identify fitment from photographs emailed to its support address
- Billet 6061 aluminum or solid 303 stainless body, depending on the option chosen
- Four cylinder grades offered, up to Medeco M3 and Abloy
- Majority manufactured in the USA, per Proven
Weaknesses
- The standard cylinder is a 7-pin tubular. The disc detainer is a paid upgrade, so a roundup crediting the 2516 with one is describing a version you have to buy
- No warranty published on the product page at all — the only lock here where that is true
- No published weight
- The base 2516 does not cover Atwood yoke latch, cast steel or Airstream couplers; those are separate model numbers
- The live manufacturer site is provenlocks.com — provenindustries.com failed TLS negotiation when we checked, which makes the brand harder to research than it should be
Fit: Proven publishes a coupler index and will identify fitment from photographs emailed to its support address. Use it — the 2516 family splits by latch design, and the base model does not cover Atwood yoke latch, cast steel or Airstream couplers.
Buy it if
You want a US-made lock matched precisely to an unusual coupler, and you are willing to pay the upgrade for a cylinder worth having.
Choose something else if
You are buying the base configuration on the strength of a roundup that credited it with a disc detainer. That is not what ships as standard.
Best close fit
AMPLock BRP-2516 Ball Coupler Lock
Why it's here
AMPLock’s approach is the opposite of universal: the body is moulded to the shape of a specific coupler lip so that, once fitted, there is nowhere to insert a tool. That is a genuine security argument rather than a marketing one, and the disc cylinder with an anti-drill rotating face backs it up.
It is also why lip style is not negotiable here. Straight lip only. Check before ordering, and register the lock when it arrives — the five-year term depends on it.
Full specifications
| Lock Type | Coupler lock |
|---|---|
| Coupler Sizes | 2-5/16 in only — the 2 in version is the separate BRP-2 |
| Coupler Styles | Straight-lip (flat lip) ball couplers only |
| Cylinder Type | Disc cylinder with a rotating face intended to resist drilling |
| Material | Ductile iron and stainless steel |
| Weight (lb) | 10 (Ultimate BRP model; Strong TLS is a separate model) |
| Dimensions | 7 x 6 x 8.5 in (Ultimate BRP model) |
| Corrosion Resistance | Stated suitable for all climates |
| Country Of Origin | Canada |
| Warranty | 5 years with registration |
Specifications verified October 4, 2026 from AMPLock flat-lip range — BRP-2516 selected, 2-5/16 in Ultimate , AMPLock flat-lip ball coupler lock range page .
Strengths
- Moulded to the coupler shape rather than clamped over it, which closes the gap a pry bar needs
- Disc cylinder with a rotating face intended to resist drilling
- Ductile iron and stainless steel, stated as suitable for all climates
- 5-year warranty
- Sold in two weights, so there is a lighter version if 10 lb on the tongue is too much
Weaknesses
- Straight-lip couplers only. A rolled or round-lip coupler needs a different AMPLock model — the close fit is exactly what makes this a hard requirement
- The 5-year warranty is conditional on registering the product
- The Ultimate and Strong versions are 10 lb and 5 lb respectively and are easy to confuse when ordering
- Retail listings appear under both U-BRP2516 and BRP-2516
Fit: Straight-lip couplers only. A round or rolled-lip coupler needs a different AMPLock model — the moulded body is what closes the tool gap, and it is also what makes lip style a hard fitment requirement rather than a preference. BRP-2516 is the 2-5/16 in Ultimate variant; BRP-2 is the separate 2 in version, and TLS-2516 is the Strong version.
Buy it if
You have a straight-lip coupler and want the tightest fit available, with a disc cylinder and a real warranty term.
Choose something else if
Your coupler has a rolled or round lip, or you are not certain which you have.
Best hitch pin lock
BOLT 5/8 in Receiver Lock
Why it's here
The problem BOLT solves is behavioural rather than mechanical. Hitch pin locks go unused because the key lives in a drawer, and a lock in a drawer is not a lock. Learning the ignition key removes the reason people stop bothering.
The mechanism is worth understanding before you buy, because it is irreversible: spring-loaded plate tumblers align themselves to the key the first time it is turned, and BOLT states plainly that its locks cannot be reset. That is a deliberate security decision, and it means the very first insertion has to be the right key on the right vehicle.
Full specifications
| Lock Type | Receiver / hitch pin lock |
|---|---|
| Pin Diameter | 5/8 in |
| Receiver Size | 2 in receivers (a 3 in variant is listed for Ford Super Duty) |
| Keying | Permanently learns the vehicle's own ignition key on first use — no second key to carry |
| Key Mechanism | Spring-loaded plate tumblers move to match the key and are permanently set the first time the key is turned |
| Reprogrammable | No |
| Cylinder Type | Plate tumbler with a sidebar, stated to resist picking and bumping |
| Material | Stainless steel pin |
| Locking Mechanism | Double ball bearing, with an auto-return spring that locks when the key is removed |
| Weather Protection | Weatherproof design |
| Vehicle Support | Ford, Chevy, GMC, Chrysler, Dodge, Ram, Jeep, Toyota and Nissan, broadly mid-1990s onward |
| Key Requirement | Exact supported mechanical vehicle-key variant; verify year and key illustration |
| Warranty | Limited lifetime, covering mechanical failure during vehicle ownership |
Specifications verified August 12, 2026 from Key-family qualification reviewed 2026-11-06 — BOLT lists a separate center-cut-key variant for specified newer Ford applications; use the vehicle finder rather than a blanket double-sided-key restriction , BOLT Lock FAQ — key-learning mechanism, no-reset limitation, supported vehicles, key requirements, warranty , BOLT 5/8 in receiver lock model pages by vehicle key family , BOLT 2025 product catalog (PDF) .
Strengths
- Opens with the tow vehicle’s own ignition key, so there is no second key to lose
- Stainless pin with a double ball bearing mechanism and an auto-return spring that locks when the key is removed
- Plate tumbler cylinder with a sidebar, stated to resist picking and bumping
- Limited lifetime warranty covering mechanical failure
- The least expensive item on this page
Weaknesses
- It permanently learns the first key used in it and cannot be reset — insert the wrong key once and the lock is finished
- It does not transfer to a new tow vehicle, which is what the "during vehicle ownership" warranty wording is really telling you
- Requires the exact supported mechanical vehicle-key variant; check BOLT’s vehicle finder and key illustration
- Compatibility depends on vehicle year and key family; some newer Ford applications use a center-cut key variant
- Retains the ball mount; does not secure the separate coupler latch or an unhitched trailer
Fit: Buy the variant matching your vehicle's key family, and be certain about the vehicle before first use. The lock cannot be reset, so it does not transfer to a new tow vehicle and a change of ignition key ends its useful life.
Buy it if
You leave a ball mount in the receiver and want a lock you will actually use, on a supported vehicle you plan to keep.
Choose something else if
You change tow vehicles often, or you drive something outside the supported makes.
Best for keying several locks alike
PACLOCK 80-Series Locking Hitch Pin
Why it's here
PACLOCK sells this the way commercial padlocks are sold rather than the way trailer accessories are, and that is the appeal. Rekeyable cylinders, a choice of cylinder grade, and the option to order several locks to a key code you specify are all normal in commercial security and almost unheard of in this aisle.
The cost is the ordering experience. The 80-series covers pin codes from 125 to 600, and PACLOCK does not publish which of those suits a 2-inch receiver against a 1-1/4-inch one. We are not going to guess at a pin diameter on their behalf — confirm it with PACLOCK before ordering, which is a phone call they answer.
Full specifications
| Lock Type | Receiver / hitch pin lock |
|---|---|
| Pin Diameter | Varies by model. The TL80S-125 is a 1/2 in pin; PACLOCK does not publish a pin-to-receiver chart on the 80-series page |
| Receiver Size | Models cover 1-1/4 in through 3 in receivers — the 125-250 kit is sold as covering 1-1/4 in plus 2, 2.5 and 3 in |
| Pin Length Codes | 125, 130, 200, 225, 250, 300, 400, 450, 455, 500, 600 |
| Cylinder Type | Three grades offered — UCS, standard rekeyable, and high-security rotating disc |
| Rekeyable | Yes |
| Keyed Alike | Can be ordered keyed to a number you specify, so several locks share one key |
| Material | High yield strength stainless steel pin; 6061 aluminium body, anodised or 304 stainless |
| Keyways | P0 or PR1 |
| Included | PAC-BAND, cotter pin and two keys |
| Country Of Origin | Made in USA with global components |
| Warranty | Not published on the 80-series product pages |
Specifications verified August 12, 2026 from PACLOCK 80-Series hitch pin locks product page — materials, cylinder grades, keyways, size codes, origin , PACLOCK TL80S stainless steel locking hitch pin lock body , PACLOCK locking hitch pin kit for 1-1/4 in and 2, 2.5, 3 in receivers .
Strengths
- Rekeyable, with three cylinder grades offered including a high-security rotating disc
- Can be ordered keyed to a number you specify, so a trailer, gate and job box share one key
- High yield strength stainless pin, with 6061 aluminum, anodised or 304 stainless bodies
- Made in USA with global components
- Ships with a PAC-BAND, cotter pin and two keys
Weaknesses
- PACLOCK publishes no pin-diameter-to-receiver chart on its 80-series page, so ordering correctly means phoning or emailing them
- The model suffix encodes pin length rather than receiver class, which makes the range genuinely confusing to shop
- No warranty terms published on the 80-series product pages
- Considerably more expensive than a commodity locking pin
- Retains the ball mount; does not secure the separate coupler latch or an unhitched trailer
Fit: Order by receiver size and confirm the pin diameter with PACLOCK before buying — the model suffix encodes pin length rather than receiver class, and the company answers fitment questions by phone and email. The keyed-alike option is the reason to choose this over a cheaper pin.
Buy it if
You already carry too many keys and want the trailer, the gate and the toolbox on one — or you want a cylinder you can rekey rather than replace.
Choose something else if
You want to order in two minutes without contacting the manufacturer about fitment.
How to choose
Match the lock to what you are protecting. A trailer parked on a driveway for months needs a coupler lock with a disc cylinder and enough steel to make an attack loud. A ball mount left in a receiver overnight needs a pin lock that costs a fraction as much.
Check ball size, coupler design and clearance. An adjustable lock reduces variant selection; it still has to seat and close as its maker specifies.
Check where the warranty conditions are. AMPLock’s five years require product registration. BOLT’s lifetime cover runs during your ownership of the vehicle — which matters unusually much here, because the lock permanently learns the first key used in it and cannot be reset, so it does not follow you to a new tow vehicle. Proven publishes no warranty on its product page at all.
Think about the key you will actually carry. The reason hitch pin locks go unused is a separate key nobody can find. BOLT solves that by learning your ignition key; PACLOCK solves it by letting you order several locks keyed to one number, so the trailer, the gate and the job box share a key.
Buy corrosion resistance if the lock lives outside. Stainless pins and sealed or capped cylinders are the difference between a lock that opens next spring and one that has seized. This is the most common real-world failure in the category, well ahead of theft.
What we left out, and why
Several widely recommended budget coupler locks. A lock-security publication that ranks on this same search maintains a do-not-buy list naming Master Lock’s 389DAT, 379ATPY and 377 coupler locks, the Reese Towpower coupler lock and the Tow Smart coupler lock, describing them as having a poor lock core and a weak body and being easily bypassed. Its basis is published bypass demonstrations by lock-picking channels rather than laboratory testing, and we have not repeated that work — but the demonstrations are public, the models are named, and those same locks appear as recommended picks on most of the pages currently ranking for this query. We are not going to recommend a lock while that evidence sits unaddressed.
Marketplace brands with no documentation. The roundups competing for this search recommend a long tail of names — NiwNiw, CZC AUTO, Kohree, RETRUE, Funmit, InfiniteRule, Vehiclex among them — that publish no specification sheet, no warranty terms and no cylinder detail. There is nothing to verify, so there is nothing for us to say about them.
Ft. Knox Locks. A genuine alternative to Proven at a similar level, built as a surround hasp taking a separate replaceable puck lock rather than an integrated one. It is not on this page because the two are best judged against each other directly — see Proven Industries vs Ft. Knox, which is the shortlist RV owners keep arriving at on forums.
CURT and Trimax receiver locks. Both are real products from real manufacturers and both appear on competing lists. CURT’s site returned an error to us on every attempt, so we could not read its specifications from the source, and we do not publish specifications we have not seen at the manufacturer. They may well earn a place here once we can.
Fifth-wheel king pin locks and gooseneck locks. Different products for different rigs, and they deserved their own page rather than three lines at the bottom of this one — so they have one. See the best fifth wheel king pin locks, where only one of the four manufacturers publishes a warranty term at all.
Questions worth answering
What is the difference between a hitch lock and a coupler lock?
A receiver or hitch-pin lock retains the ball mount in the tow vehicle. A storage coupler lock fills or encloses an unhitched trailer's ball socket. A latch-pin lock secures a compatible coupler latch, which is a separate connection from the receiver pin. None secures every part of the hitch or guarantees protection against theft.
Will any coupler lock fit my trailer?
No, and this is the most common reason a lock gets returned. Ball size — 1-7/8, 2 or 2-5/16 inch — is only half the answer. The latch design matters too, and the better locks are sold as a separate variant for each one. B&W lists ICON variants by coupler design, and Proven splits the 2516 into trigger and thumb latch, Atwood yoke latch, cast steel and Airstream versions. An adjustable lock such as Fastway Fortress reduces variant selection, but still needs to seat and lock on the actual coupler.
Can a determined thief get past a coupler lock?
Yes. Resistance depends on the exact lock, installation and attack. Manufacturer demonstrations do not establish a universal defeat time or a guarantee against theft. Treat locks as one part of the storage plan.
Are the cheap coupler locks on Amazon worth buying?
Several of the most widely recommended budget coupler locks have been publicly demonstrated being opened or bypassed in seconds by lock-picking channels, and a lock-security site maintains a do-not-buy list naming them. Marketplace brands with no documentation are worse again — there is nothing published to check. If the budget is tight, a mid-price universal lock from a named manufacturer is a real purchase; a $20 cast-zinc lock is a visual deterrent and should be bought as one.
Do I need both a coupler lock and a hitch pin lock?
They serve different locations. For an unhitched trailer, start with a storage coupler lock that fits. A receiver lock retains the ball mount. When parked while hitched, also assess the coupler latch: locking the receiver pin does not stop the latch being released. Use compatible hardware and follow the hitch and coupler makers' instructions.
What lock cylinder should I look for?
Check the exact cylinder supplied with the variant you order. Proven's base 2516 uses a tubular cylinder and offers a disc-detainer upgrade. Cylinder type alone does not establish an attack-resistance grade; construction, shielding, fit and independent testing also matter.