ABUS ACH Classic AdptrChn + FrmLockThe ABUS ACH Classic Adapter Chain provides a secondary layer of security when used with an existing frame lock. This hardened steel chain allows cyclists to tether their bicycle to a fixed object such as a lamppost or fence. It functions as a convenient extension that increases the range of locking options for urban or short term storage. The system works by looping the chain around an anchor point and inserting the locking bolt into the frame lock