Starts with your car's ignition key, eliminating the need for additional keys on your keychain. Compatible with Chevy, GMC, Buick, and Cadillac keys with a center cut. Suitable for couplers ranging from 1/2" to 3-3/8" in width. The lock smoothly glides along a stainless steel pin for easy operation, with 1/8" incremental adjustments for a secure fit. Features a stainless steel lock shutter to keep dirt and moisture out, as well as a plate tumbler sidebar for added security against picking and bumping. Includes a Limited Lifetime Warranty.