Trimax UMAX Trailer Locks are built tough and constructed out of steel. Provides instant security and gives you peace of mind knowing your trailer is staying where it belongs. Built with a dual-ratchet locking system that keeps your trailer secure and deters thieves. Installs in seconds by sliding ball up into coupler and replacing U-shackle. One size fits all from 1-7/8" to 2-5/16", all coupler types. Includes 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.