The UMAX 100 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 hooked up to your vehicle. Features 1/2 turn technology that cannot be false locked. •One size fits all (from 1 7/8", 2", to 2 5/16", all coupler types) •Key hole cover slides up to seal out dirt and grime •Attractive ballistic grade nylon housing absorbs hammer blows and protects against weather •Type A key which is a spring loaded, 7 pin, high security key. Resists attempted drill outs. Rugged and durable, the key will not bend or break.