Best Trailer Coupler Locks
Our top picks
Proven Industries Model 2516
Custom fit wraps the coupler, little room for tools.
About $250 (provenlocks.com list)
Check price at Proven ↗Proven Industries Model 2178
Custom fit for 2 in couplers.
Check current price
Check price at Proven ↗AMPLock
Custom-fit range for many coupler types.
Check current price
Check price at AMPLock ↗
Comparison
| Lock | Best for | Fits | Price (approx.) | |
|---|---|---|---|---|
| Proven Industries Model 2516 | Best overall (2-5/16 in) | Most 2-5/16 in trigger- and thumb-latch couplers | About $250 (provenlocks.com list) | Check price ↗ |
| Proven Industries Model 2178 | Best overall (2 in) | Most 2 in couplers | Check current price | Check price ↗ |
| AMPLock (coupler, gooseneck, kingpin, hitch, latch pin, door locks) | Best custom-fit alternative | Coupler (boat, RV, cargo), gooseneck (Bulldog, Atwood), kingpin, hitch 1-1/4 to 3 in, latch pin, barn/roll-up door | Check current price | Check price ↗ |
| Trimax UMAX100 | Best universal | Most 1-7/8 in, 2 in and 2-5/16 in couplers | About $130 (trimaxlocks.com list) | Check price ↗ |
| Blaylock TL-34 EZ Lock | Best push-button aluminum | 2-5/16 in trigger-style couplers (Atwood, Fulton, Shelby, Titan, Demco and similar) | Check current price | Check price ↗ |
| Blaylock TL-33 Universal | Best for latch couplers | Many trigger, latch and hand-wheel couplers, 1-7/8 to 2-5/16 in | Check current price | Check price ↗ |
| Master Lock 389DAT | Best budget | Most 1-7/8 in, 2 in and 2-5/16 in couplers incl. surge-brake, rolled-lip, UFP | About $36 (masterlock.com list) | Check price ↗ |
How we chose: picks are based on published specifications, materials, fit charts, manufacturer information and patterns in owner reports. We have not lab-tested these locks. Prices are approximate list prices seen on maker sites in October 2026 and change often.
Our picks in detail
Proven Industries Model 2516
Who it is for: Owners of valuable 2-5/16 in trailers stored unattended.
- Custom fit wraps the coupler, little room for tools
- 1/4 in steel, tubular key
- Keyed-alike option across the range
- Can capture most safety chain hooks
- Expensive
- Must match your exact coupler model
- Heavy
- Type: Coupler lock (custom-fit)
- Fits: Most 2-5/16 in trigger- and thumb-latch couplers
- Build: 1/4 in steel, black powder coat, puck lock, 7-pin tubular key
- Keyed alike: Yes (keyed-alike option across Proven line)
- Price: About $250 (provenlocks.com list)
Can secure most 5/16 in safety chain hooks per maker; check the fit index for your coupler.
Check price at Proven ↗Proven Industries Model 2178
Who it is for: Boat and utility trailers with 2 in couplers wanting top security.
- Custom fit for 2 in couplers
- 1/4 in steel
- Keyed-alike option
- Price not confirmed on our check
- Fit is coupler-specific
- Type: Coupler lock (custom-fit)
- Fits: Most 2 in couplers
- Build: 1/4 in steel, black powder coat, puck lock
- Keyed alike: Yes (keyed-alike option)
- Price: Check current price
2 in version of Proven's coupler lock (spec per dealer listing at nctrailers.com).
Check price at Proven ↗AMPLock (coupler, gooseneck, kingpin, hitch, latch pin, door locks)
Who it is for: Owners who want custom-fit security and a fit-finder.
- Custom-fit range for many coupler types
- 5-year warranty with registration
- Fit quiz on maker site
- Prices not confirmed on our check
- Heavy
- Type: Custom-fit lock range
- Fits: Coupler (boat, RV, cargo), gooseneck (Bulldog, Atwood), kingpin, hitch 1-1/4 to 3 in, latch pin, barn/roll-up door
- Build: Heavy-duty steel, custom-fit; fit quiz on site
- Keyed alike: Check per model
- Price: Check current price
5-year warranty with registration (per maker).
Check price at AMPLock ↗Trimax UMAX100
Who it is for: Owners wanting more security than budget locks without custom-fit prices.
- Hardened steel with nylon housing
- Fits 1-7/8, 2 and 2-5/16 in
- Keys alike with other Trimax locks
- Universal fit, not glove-tight
- Bulkier than budget locks
- Type: Universal coupler lock
- Fits: Most 1-7/8 in, 2 in and 2-5/16 in couplers
- Build: Solid hardened steel, ballistic nylon housing, 9/16 in shackle
- Keyed alike: Keys alike to other Trimax locks (per catalog)
- Price: About $130 (trimaxlocks.com list)
Blaylock TL-34 EZ Lock
Who it is for: Owners of 2-5/16 in trigger-style couplers.
- Push-button, no padlock needed
- Cast aluminum, made in USA
- 2-5/16 in trigger couplers only
- Price not confirmed on our check
- Type: Push-button coupler lock
- Fits: 2-5/16 in trigger-style couplers (Atwood, Fulton, Shelby, Titan, Demco and similar)
- Build: Cast aircraft-grade aluminum, hardened steel pin, made in USA
- Keyed alike: -
- Price: Check current price
TL-36 and TL-38 cover other sizes.
Check price at Blaylock ↗Blaylock TL-33 Universal
Who it is for: Latch-style coupler owners.
- Fits many trigger, latch and hand-wheel couplers
- Simple bracket design
- Padlock not included
- Security depends on your padlock
- Type: Bracket coupler lock (padlock required)
- Fits: Many trigger, latch and hand-wheel couplers, 1-7/8 to 2-5/16 in
- Build: Aluminum bracket, 3/4 in steel pin; padlock not included
- Keyed alike: Depends on your padlock
- Price: Check current price
Master Lock 389DAT
Who it is for: Boat and utility trailers on a budget.
- Low price
- Wide fit incl. surge-brake couplers
- Bright red is a visible deterrent
- Cannot be keyed alike
- Universal fit leaves room to pry
- Type: Universal coupler (ball) lock
- Fits: Most 1-7/8 in, 2 in and 2-5/16 in couplers incl. surge-brake, rolled-lip, UFP
- Build: Red powder-coated steel, wafer tumbler, keyway cover
- Keyed alike: No (cannot be keyed alike)
- Price: About $36 (masterlock.com list)
Bright red as a visual deterrent.
Check price at Master Lock ↗
How to choose
- Ball size: read the size stamped on your coupler (1-7/8 in, 2 in or 2-5/16 in). Custom-fit locks are sold per size; universal locks cover all three but fit looser.
- Coupler type: trigger latch, thumb latch, lever/latch style (Atwood-type), surge-brake (common on boat trailers) or cast-steel. Custom-fit makers publish fit charts; check yours before buying.
- Material and coverage: thick steel that wraps the whole coupler leaves less room for pry bars and cutters than a small ball plug with an exposed shackle.
- Lock cylinder: tubular and disc cylinders resist picking better than basic wafer locks. Look for a keyway cover so dirt and road salt stay out.
- Keyed alike: if you also lock the hitch pin, spare tire or doors, a keyed-alike set means one key for everything.
- Weather: powder coat, stainless pins and sealed keyholes matter if the trailer sits outside or near salt water.
Identify your coupler first
Look for the ball size and brand stamped on the coupler (Atwood, Fulton, Bulldog, Demco, Titan and so on). Take a photo. Custom-fit makers such as Proven publish a coupler index and will confirm fit from a photo; buying the wrong custom lock is the most common mistake.
Safety chains
Some full-coverage locks can also capture the safety chain hooks. Proven says most of its coupler locks can secure 5/16 in chain hooks, though it cannot guarantee every hook size.
Our pick
Proven Industries Model 2516: best overall (2-5/16 in). Owners of valuable 2-5/16 in trailers stored unattended. If budget matters more, see the other picks above.
Check price at Proven ↗FAQs
- What is the best coupler lock?
- For maximum security, a custom-fit steel lock from Proven Industries or AMPLock. For a lower price, a universal lock like the Trimax UMAX100.
- Are universal coupler locks secure?
- Reasonably, but the looser fit leaves more room to pry. They are a big step up from no lock.
- How do I measure my coupler?
- The ball size is stamped on top of most couplers. If it is worn, measure the socket opening or contact the maker with a photo.