Trimax T3FL Premium 5/8" Key receiver Lock with Flat Key The 5/8" pin fits all Class III, IV and V receiver hitches 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 Strongest locking pin on the market 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.