Reese Towpower Universal Coupler Lock prevents your trailer from being towed by anyone else while it"s unhitched from your vehicle. It guards against trailer theft with heavy duty cast steel construction and an advanced locking mechanism which resists picking and prying. A ratchet design with six locking positions works with a range of couplers (1 7/8, 2, and 2 5/16 inches). It also features a protective, weather-resistant zinc finish to resist rust.