Reads a cat's existing identification microchip (no collar required) compatible with all international microchip formats stores up to 32 microchip numbers runs on 4 x AA batteries for over 12 months two part construction for easier installation fits into doors up to 6cm thick with no accessories. the microchip cat flap can also be installed in glass from 3mm to 6cm in thickness a glass mount adaptor will be required for all glass installations. for non-microchipped pets you can use the SureFlap collar tag Measurements: Hole: 165x171mm Flap: 142x120mm Outer area: 210x210mm