Trimax 4010236 Umax50 Premium Die-Cast Dual Purpose Coupler Lock One size fits all coupler types Dual ratchet lock System Exclusive design provides 360 degrees of hardened steel protection Key hole cover keeps out dirt Rust proof hammer tone epoxy finish One size fits all (from 1-7/8", 2", to 2-5/15", all coupler types) Key hole cover slides up to seal out dirt and grime 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. Huge 6 tooth, 3/8" dual ratchet locking system Hardened 5/8" 16mm steel shackle