Description Our innovative Electronic SmartDoor™ gives your pet a key to the house so he can come and go as he pleases. Using radio-frequency technology, the SmartDoor™ reads the unique signal of a SmartKey™ worn on your pet’s collar and triggers the battery power-driven flap to unlock. When the SmartDoor™ no longer senses your pet’s SmartKey™, the flap automatically locks back into place. WARNING: Small children can pass through door. Read Entire Statement Features Easily program up to 5 SmartKeys™ with a touch of a buttonSystem Includes One programmed SmartKey™ and battery included Operating Guide More Info The SmartDoor™ can detect up to five programmed SmartKeys™ and also operates in two other modes: fully locked mode and unlocked mode. Locked mode does not allow entry or exit for any pet and unlocked mode allows entry and exit for all pets.