Includes 2 electronic I.D. Discs (up to 8 unique I.D.Discs possible) to control individual entry and exit through the flap - keeps all other animals out. LCD Display shows selected entry and exit lock status, cat location and time since flap last used for up to 3 selected cats. Low battery indicator. Requires 4 x AA (R6) batteries. Timer function controls access for all your cats, e.g. to keep cats in at night. Self-lining up to 50mm (2") thick - ideal for all single/double glazing and any panel 0 - 50mm (0 - 2") thick. Wall Liner available for wall installation. Fully draft and weatherproof brush sealed flap.