Identify CURT Posi-Lock Couplers: 25128, 25100, 25135 & More
Older straight-tongue couplers can look almost identical after their labels wear away. CURT's Posi-Lock mechanism uses a spring-and-nut adjustment across several models, but the ball socket, mounting channel and rated towing load differ. Compare the physical opening and original model number before selecting a replacement.
Identify the original CURT Posi-Lock model
| Part number | Ball | Mounting size | Max GTW | Max TW |
|---|---|---|---|---|
| 25128 | 1⅞ in | 2 in straight channel | 2,000 lb | 200 lb |
| 25153 | 2 in | 2 in straight channel | 3,500 lb | 500 lb |
| 25135 | 2 in | 2½ in straight channel | 3,500 lb | 500 lb |
| 25138 | 2 in | 3 in straight channel | 3,500 lb | 500 lb |
| 25100 | 2 in | 3 in straight channel | 5,000 lb | 700 lb |
| 25210 | 2 in | A-frame | 5,000 lb | 700 lb |
The two couplers for a 2-inch-wide straight tongue are not the same: 25128 is designed for a 1⅞-inch hitch ball and rated to 2,000 lb GTW, while 25153 takes a 2-inch ball and is rated to 3,500 lb. CURT 25135 fits a 2½-inch channel and 25138 fits a 3-inch channel; both connect to 2-inch balls at 3,500 lb GTW.
Model 25100 also has a 3-inch straight channel and 2-inch-ball socket, but is rated to 5,000 lb GTW. The black 25210 is a 5,000 lb A-frame coupler, not a channel-style replacement.
Check both ratings and every connection. Gross trailer weight (GTW) and tongue weight (TW) are separate limits. A higher-rated coupler does not increase the rated capacity of the trailer, hitch ball, ball mount, vehicle or frame. The hitch ball diameter must match exactly; a 1⅞-inch-ball coupler is not compatible with a 2-inch ball.
Replacement identification checklist
- Locate the part number. Check the coupler label, stamped markings and original documentation. Confirm the complete five-digit CURT identifier.
- Check the ball socket. Measure or identify the rated ball size; the 25128 uses 1⅞ inches while the five other listed models use 2 inches.
- Measure the tongue arrangement. For a straight tongue, determine whether the existing channel is 2, 2½ or 3 inches wide. An A-frame is a separate mounting type.
- Read the rating before replacement. Two models can share channel and ball dimensions while having different GTW and TW limits; do not use the appearance of the latch to infer capacity.
- Inspect the Posi-Lock mechanism. Look for damage, adjustment issues, lost safety hardware, corrosion and wear at the ball socket. Replace defective couplers with properly rated components.
- Confirm the installation. Compare mounting holes, fasteners or structural welding, and check the trailer manufacturer's requirements before fitting a different part number.
Recognize the A-frame version
The black CURT 25210 mounts to an A-shaped trailer tongue and has a 2-inch ball socket with a 5,000 lb GTW rating. Its tongue-mount geometry distinguishes it from the zinc-plated straight-channel models, even though the latch mechanism is similar.
Match the part number to its catalog listing
All six UsedRVParts records are categorized as Brand New. Open the exact listing for availability, package details and fulfillment options. Viewing and pickup of eligible Kelowna items are by appointment.
More trailer connection references
For identification of related towing hardware, see our CURT latch-pin identification, DeadBolt coupler lock identification and Husky coupler identification. Confirm the specific components independently before combining them.
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