The Evolution Series 4 Integrated Chains are for convenient bicycle protection in moderate to high crime areasThe hardened triple heat-treated boron manganese steel chains include 10mm six-sided linksThe integrated chains secure with a new patent-pending integrated Evolution series 4 lock headThis innovative series of chains also feature a patent-pending pin-less design which secures the chain to a hardened deadbolt and allows for no weak leak in the chain due to extensive holding power of the link itself against attacksChains are enclosed in a nylon-webbing sleeve to protect paint from scratches and allow for easy portability and tight coiling during storageComes with 3 stainless steel keys including a lighted LED key with replaceable battery and 2 new, ergonomic \'I\' keysOne key is lighted for easy access at night; replaceable battery insures that light can be used as long as the lock. The new \'I\' keys make opening a disc-style cylinder much smoother.