Kryptonite Evolution Series-4 1055 Mini Integrated Chain Bicycle Lock Bike Lock (21.5") 10mm six-sided chain links made from3T MANGANESE STEEL Patent-pendingEND LINK DESIGNsecures chain to hardened deadbolt eliminating critical vulnerability HIGH SECURITY DISC-STYLE CYLINDERis pick and drill resistant Patented*, reinforcedOVAL CROSSBAR LOCK HEAD SLIDING DUSTCOVERprotects and extends cylinder life 3 STAINLESS LSTEEL KEYS one LED lighted key with replaceable battery and 2 new, ergonomic I keys DurableWEATHER-RESISTANTnylon sleeve prevents scratches Key Safe Program Product dimensions: 21.5 (55cm) chain length Product weight: 4.40 lbs (2.00 kgs) 10mm six-sided chain links made from 3t manganese steel Patent-pending end link design secures chain to hardened deadbolt eliminating critical vulnerability High security disc-style cylinder is pick and drill resistant Patented*, reinforced oval crossbar lock head Sliding dustcover protects and extends cylinder life 3 stainless steel keys  one LED lighted key with replaceable battery and 2 new, ergonomic I keys Durable weather-resistant nylon sleeve prevents scratches Key Safe Program