If your pet is not microchipped, the SureFlap RFID Collar Tag is available as an alternative*. SureFlap collar tags contain a code that is unique to your pet so that if other pets in the neighbourhood have a SureFlap collar tag, or any other type of collar tag used in selective pet doors, they will not be able to gain access.  Key points  Compatible with all versions of the SureFlap Microchip Pet Door  Compatible with the SureFlap Microchip Cat Door with serial numbers higher than 1152201  For use with non-microchipped pets  Each collar tag has a unique code  Each pack contains two collar tags  Collar tag diameter: 25mm  Weighs just 2g