The CAT Card 2 and CAT Card 4 Systems are full featured access control systems. These systems are available in 2 door (CAT Card 2) and 4 door (CAT Card 4) configurations and can be linked by using the MUI (Multi Unit Interface) Option. The systems can be expanded to control up to 16 doors and 255 relays point for control of elevators, HVAC, lights or other facility control points that require activation or monitoring (using optional CAT Card Reader expansion and Relay Expansion modules). The CAT Card systems can be interfaced with the CAT Series. The LCD and keypad mounted inside the unit housing allows easy programming or the units can be programmed via SELCOM if a phone line is connected or an optional Serial card plugged on to the unit.