Opens with your vehicle ignition key. Fits couplers from 1/2 in. to 3 3/8 In. and any size in between. Stainless steel pin. Lock slides back and forth along pin for ease of use. 1/8 in. incremental adjustments allows for a snug fit. Weather proof. Plate tumbler sidebar to prevent picking and bumping. Stainless steel lock shutter to keep out dirt and moisture. Limited lifetime warranty.