Key Features I.D Disc / Tag for Elite Super Selective Cat Flap For Creating Individual Unique ID’s Blue Colour Wipe Clean Genuine Pet Mate The Cat Mate Electronic ID Disc is an additional tag for use with the Elite Microchip Cat Flap by Pet Mate. Working by a radio frequency signal these ID Discs are essential for each cat, as each tag has a unique identifier on them which allows your cat access in and out of the flap. Specifications I.D Disc Dimensions: 35mm x 35mm x 3mm Works with - Elite ID Disc Cat Flap and Timer - (305) Elite Microchip Cat Flap with Timer - 355 Elite Microchip Cat Flap (356)