Using radio-frequency technology, the SmartDoor™ Electronic Pet Door reads a unique signal of the SmartKey™ Electronic Key and triggers the flap to unlock so your pets can come and go as they please. When the SmartDoor™ Electronic Pet Door no longer detects your pet’s SmartKey™ Electronic Key, the flap automatically locks back into place. The SmartDoor™ Electronic Pet Door can detect up to five programmed SmartKey™ Electronic Keys and also operates in two other modes: fully locked mode and unlocked mode. WARNING: Small children can pass through door.   KEY FEATURES * * SmartDoor™ Electronic Pet Door has 3 programmable modes: Automatic, Locked and Unlocked * * Easily program up to 5 pets with a touch of a button (one programmed SmartKey™ Electronic Key included) * * Energy efficient with an insulated UV sun protection flap * * Multi-Point Locking Flap System * * Low battery indicator   FEATURES * * Made of plastic * * Energy efficient, insulated flap with UV sun protection * * Multi-Point Locking Flap System * * Uses 4 x D-cell batteries (not included)   MORE INFORMATION Fits: * * wooden doors < 51 mm thick * * PVC / uPVC / Metal < 51 mm thick * * Fits brick walls up to 203 mm (requires Wall Entry Kit)   SYSTEM INCLUDES * * SmartDoor™ Electronic Pet Door * * SmartKey™ Electronic Key * * Battery (PetSafe® RFA-67) * * Key Ring * * 8 x Mounting Screws * * Operating Guide * Cutting Template