Trimax UMAX100 features an exclusive design that provides 360 degrees of hardened steel protection for your unattended trailer. Provides instant security for your camper, boat or trailer when they are not hook up to your vehicle. Features 1/2 turn technology that cannot be false locked. For dual force security add a TRIMAX chain or cable secured to an anchor point! Also, add a TRIMAX coupler lever lock for additional protection. Easy Installation. Slide ball up into coupler and replace u-shackle. Fits all of the following coupler and more: 1-7/8" or 2" Fulton, Atwood 2", UFP, Bulldog, 2-5/16" couplers, Fulton Heavy Duty, Surge Brake (reverse mount). Huge 6 tooth, 3/8" dual ratchet locking system. Hardened 5/8" 16mm steel shackle. TRIMAX makes the world's toughest locks.