Great Grand Master Key Arrangement: In the diagram above The locks are operated individually by separate keys. (K1 = D1, K2 = D2....) The sub master keys (SMK1, SMK2...) operate a small group of locks. Grand Master key (GMK1, GMK2...) & Master key (MK1, MK2...) open certain set of locks and Grate Grand Master key (GGMK) Opens all the locks in the system. Example: Master keys Can be used Floorwise Grand master key can be used for Building. Grate Grand Master can be used for whole project. _____________________________________________________________________ For Grate Grand Master key system just call or write an inquiry.