Master Keying /Abloy/AbloyGlobal/ABLOY%20USA/Abloy%20technology/Abloy_Tech_MasterKey.jpg Abloy locking systems can be set up several different ways. Keyed Different - Every lock is keyed to a unique combination. Keyed Alike - Two or more locks can be operated with the same key. Central Locking - Two or more different keys operate a common lock as well as individual locks. Master Keyed - All locks are operated by individual keys and by a master key. Grand Master Keyed - Locks operated by multiple levels of keys and master keys.