Identify your trailer coupler
Compare real coupler photos, then check the brand, model and marked size. Similar-looking couplers can need different locks.
Open the coupler photo guide →
Identification is the first step. Confirm the lock’s stated fit and clearance measurements before ordering.
A coupler lock protects the parked trailer connection. A puck lock secures a compatible door hasp. Start with the hardware you want to secure.
Coupler lock or hitch lock: which connection are you securing?
“Trailer hitch lock” is often used as a broad shopping term. A receiver hitch pin lock secures a ball mount or accessory inside the vehicle’s receiver. A coupler latch lock goes through the trailer latch. NIWNIW’s enclosure-style coupler locks cover compatible parked-trailer couplers to obstruct a new hookup; standalone XL puck locks secure compatible door hasps. These designs are not interchangeable.
Compare the NIWNIW trailer locks
| Application | Choose | Check first |
|---|---|---|
| Coupler and safety chains |
Coupler & Safety Chain Lock 2 in or 2-5/16 in; Silver, Black, Red or Blue |
Coupler shape, latch, room for the enclosure and safety chains |
| Multiple ball-size applications |
Multi-Size Coupler Lock Compatible 1-7/8 in, 2 in and 2-5/16 in couplers |
Actual body profile and latch clearance |
| Select Bulldog and Ram couplers |
Select Bulldog & Ram Coupler Lock 2-5/16 in |
Exact coupler profile and the product fit diagram |
| Trailer, van or truck door hasps |
XL Keyed-Alike Puck Locks Black; 2, 3 or 4 locks per pack |
Hasp dimensions, rear opening and lock-body clearance |
Three measurements to gather
- Identify the connection. Read the marked ball size on the coupler or measure the door hasp. A matching ball size alone does not confirm coupler-lock fit.
- Compare the profile. Check body shape, latch location and the surrounding hardware against the exact product photographs and dimension diagrams.
- Check installed clearance. Allow room for the jack, safety chains, wiring and brackets. Ensure the lock can close and be unlocked as instructed.
Will different packs use the same key?
Each key supplied with an XL puck-lock pack operates the locks in that purchased pack. Separate packs are not guaranteed to share a key pattern. Do not assume a coupler lock and a separate puck-lock pack use the same key.
Can any lock prevent all theft?
No lock guarantees protection against every tool or attack. Inspect your lock and trailer hardware regularly and use an appropriate security routine.
Check the details before ordering
- Coupler lock fit checklist: profile, latch and clearance
- Keyed-alike puck lock packs: key matching and hasp fit
Still unsure about the fit?
Send the product name, equipment make and model, marked coupler size and the dimensions you have measured through our contact form. Do not order based on a trailer brand name alone.