Trimax SXTC3 Premium Stainless Steel Coupler Lock (3.5" Span) Fits couplers with up to a 3-1/2" span O-ring keeps water, grime and dirt out of locking mechanism to ensure years of use Protective rubber cap protects keyhole from water, grime and dirt 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. 100% stainless steel