If you are specifically searching for automatic doggie doors that utilize RFID technology, please see Plexidor RFID dog doors.
America's Pet Store carries the largest selection of auto dog doors online. What are automatic dog doors? They are doors for your pet that are opened exclusively by a transmitter worn around your pet's neck, and are activated when your pet approaches the dog door. America's Pet Store carries a large number of different technologies of automatic dog doors including: Radio Frequency RFID, ultra sonic, infrared, electro-magnetic and magnetic technologies.