This tow clamp is perfect for locking 1. 25" and 2" hitches, compatible with most hitches classes I, II, III, and IV (1, 2, 3 and 4). Suitable for trailer truck SUV sedan RV camper van and minivan. Reduce rattle and movement for hitch tray, cargo carrier, bike rack, trailer ball mount with brands curt,highland, goplus, pro series, rola, yakima, thule, etc. High-Strength Anti-Rust U-Bolt with Rubber Isolator and Tightener Plate, 1 Rubber Isolator, 2 Spring Lock Washers, 2 Flat Washers, 4 Locking Nuts, All the Parts of Surface was Covered By Galvanize & Powder CoatedCan help to decrease noise and give you a quiet world when towing. Easy to install, after insert the tube, lock them directly by U-bolt and plate, put on original spring washers, flat washers and fasten by nuts, then done. Follow the picture to install it and also can be mounted from the bottom. If the hitch is low, and there is a risk for U-Bolt to scrap ground, lock the tightener from the bottom. Use on ball mounts, drop hitches, hitch adapters, hitch extenders and other trailer accessories. Spring lock washers and flat washers help to tightening it in place and secure.