1.25*7mm is smallest RFID Pet Microchip sized for now, which widely used for tagging fish, mice, etc such very small animals; While 2x12mm is the common sized and popularly used on the market for dog, cat, other pet etc. ICAR certified Protection: IP-68 Dust and Waterproof Sterile ISO 11784/11785 Available with injector Free Samples, 1Day Fast Delivery!