CURT Straight Tongue Trailer Coupler for 3" Channel — 2" Ball, 5,000 lb, Zinc-Plated

CURT 25100 is a heavy-duty straight-tongue trailer coupler that mounts to a 3-inch channel and secures to a standard 2-inch trailer ball with a 5,000 lb gross capacity.

When replacing or building a trailer, the coupler is the connection that keeps trailer and tow vehicle linked under load and over rough roads. The CURT 25100 combines stamped steel strength, a zinc finish for corrosion resistance, and an adjustable Posi-Lock latch so you can get a snug fit on a standard 2" ball. It’s designed for straightforward installation on most 3" wide trailer tongue channels and includes a lockable latch for added security.

How does this coupler attach to a 3-inch trailer tongue channel?

The coupling slides over a 3" channel and secures with conventional mounting hardware (bolts and nuts) through the pre-cut slot area. Its punched, die-cut steel body aligns with channel edges for a clean fit, and the internal adjustment nut lets you close any slack for a tight bearing against the trailer ball.

• Fits 3" wide mounting channel commonly used on utility and cargo trailers
• Bolts through the tongue channel for a solid mechanical connection
• Adjustable internal nut and Posi-Lock spring for fine tuning
• Designed to mate with a standard 2" diameter trailer ball

What load limits and safety features should I expect?

The CURT 25100 is rated for a 5,000 lb gross trailer weight and a 700 lb tongue weight, making it a Class III style coupler suitable for many light-to-medium trailers. The Posi-Lock latch accepts a safety pin or a coupler lock to prevent accidental uncoupling and to deter theft, while the zinc finish protects metal surfaces from rust and road wear.

• 5,000 lb gross trailer weight (GTW) rating
• 700 lb tongue weight capacity for balanced towing
• Lockable Posi-Lock latch accepts safety pin or coupler lock
• Durable zinc plating resists corrosion and road debris

How do I adjust and operate the Posi-Lock latch for a tight fit?

Operation involves placing the coupler onto the 2" trailer ball, closing the latch, then tightening or loosening the internal adjustment nut until the latch holds without excessive play. The Posi-Lock spring helps keep the latch engaged; use a clip or coupler lock through the latch hole for transport security.

• Set coupler over a 2" ball, close latch, check for play
• Turn the internal adjustment nut to remove slack
• Verify latch fully engages Posi-Lock spring
• Insert safety pin or lock for travel

Will this coupler resist weather and corrosion on boat or utility trailers?

The coupler’s zinc-plated finish significantly improves resistance to moisture, salt spray and road grime compared with bare steel. While zinc helps extend service life, periodic inspection and basic maintenance—cleaning, light lubrication, and checking fasteners—will keep the coupler functioning longer in wet or coastal environments.

• Zinc plating shields steel from rust and surface corrosion
• Recommended for boat, utility, and general-purpose trailers
• Perform routine checks and lubrication for best longevity
• Replace if deep corrosion or structural damage appears

Who is this for: The CURT 25100 is aimed at DIY trailer builders and owners who need a reliable, easy-to-adjust straight-tongue coupler for 3" channel tongues that use a 2" trailer ball. It suits light-to-medium trailers such as utility, small equipment, and boat trailers where a 5,000 lb gross capacity and a secure, lockable latch are required. Professionals and weekend tinkerers alike will value the simple installation, adjustable Posi-Lock mechanism, and zinc finish for everyday towing conditions.