Kryptonite KryptoLok Series 2 Integrated Chain Bicycle Lock New patent-pending pin-less link design secures chain to hardened deadbolt; offers no "weak" link in the chain due to the extensive holding power of the link itself against attacks 9mm four-sided chain links made of 3t manganese steel High security disc-style cylinder is pick and drill resistant; resists most common hand tools Weather-resistant nylon sleeve prevents scratches to painted finishes; compact coiling for easy carrying Includes 2 ergonomic "I" keys