Abstract: A lock with an improved configuration comprises a housing and a cylindrical member mounted in the housing. A lock core is mounted in the cylindrical member. The lock is characterized in that the cylindrical member comprises either nine or eleven pin recesses at the front end, a disc and an engaging post having a dodecagonal section are mounted at the front end of the lock core, and the disc comprises nine through passages and three openings of different depths. Based on the configuration of the lock, the key to be inserted into the lock must have a dodecagonal inner passage to match the dodecagonal section of the engaging post of the lock. Because of the three openings of different depths, a thief cannot use specialized tools to explore the lock and unlock the lock. The number of codes of the lock is increased to keep the lock from being easily unlocked. The owner's property and privacy of are thus protected.