Keeper 712 Integrated Chain Lock features 7mm four-sided chain links made from 3t manganese steel. Patent-Pending End Link Design secures chain to hardened deadbolt eliminating critical vulnerability and providing extra holding power. High security disc-style cylinder is pick and drill resistant; resists most common hand tools. Durable weather-resistant nylon sleeve prevents scratches to painted finishes and protects the chain against the elements. With a 48-inch (120cm) chain length, the Kryptonite Keeper 712 is a flexible, compact and easy to use deterrent security.