The Kryptonite Keeper 785 Integrated Chain Bike Lock ensures your bikes safety without having to worry about any damage to your bike frame with the protective nylon sleeve. The Keeper 785 uses a heavy duty, 7 mm four-sided chain links made from 3T manganese steel with a new end link design that secures to a hardened deadbolt. The high security disc-style cylinder is pick and drill resistant to give you a peace of mind.