The UMAX 25 features an exclusive design that provides 360 degrees of hardened steel protection for your unattended trailer. For easy installation, simply slide the ball up into coupler, and replace U-shackle. The coupler lock with a dual-ratchet lock system provides instant security for your camper, boat, or trailer when they are not hooked up to your vehicle. Constructed from premium solid hardened steel with a rugged, corrosion-resistant finish. 1/2" steel shackle. Fits most 1-7/8", 2", and 2-5/16" couplers. Working width: 4". Includes two rugged tubular keys.