PetSafe Pet SmartDoor SmartKey - One Size Fits All Black

729849110458 This extra SmartKey can be used for an additional pet using your Electronic SmartDoor. PetSafe's innovative Smart Door recognizes the SmartKey worn on your pet’s collar and unlocks the pet door. After your pet has passed through and the SmartDoor no longer senses your pet's SmartKey, it automatically locks back into place. Each SmartDoor can program up to 5 SmartKeys. The SmartKey is for use with the Small Electronic SmartDoor and the Large Electronic SmartDoor.