The Chain Lock Steel-O-Chain 4804K is the perfect choice when time is of the essence. The automatic cylinder allows the bike to be locked without a key. Simply open the lock and press the locking bolt into the lock body--job done. The bike lock is ideal for securing low-cost bikes and children's bikes in areas with a low risk of theft. - 4mm thick square chain with textile sleeve that prevents damage to paintwork - The chain is made of specially hardened steel