Designed for cats without embedded microchips, entry and exit is operated by unique electronic I.D. Discs (2 supplied) for up to 9 cats - keeping all other animals out. Individual entry and exit control. 4 way lock control. 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 batteries (not included) which will give approximately 12 months operation. Timer function controls access for all your cats, e.g. to keep cats in at night. Self-lining up to 50mm thick - suitable for all single/double glazing and any panel 0 - 50mm thick including metal. Wall Liner available for wall installation (not included). Fully draft and weatherproof brush sealed flap. Product Dimensions: W 248mm x H 265mm x D 95mm. Cut out size 16.6cm wide x 19.2cm high or 23.2cm diameter for circular cut out. Please note that this item does not work with embedded microchips, only Cat Mate I.D. Discs ref. 310.