PetSafe Small Smart Door

 When the SmartDoor no longer senses your pet's SmartKey, the flap automatically locks back into place. The SmartDoor can detect up to five SmartKeys and has 3 modes - Automatic, Locked and Unlocked. The energy efficient, insulated flap features UV sun protection. Requires 4 D-cell batteries, not included. Fits door thickness 3.8cm - 5cm. Door dimensions 22.9cm x 40cm. Flap opening dimensions 14cm x 20cm. Great for pets up to 15 lbs.