The Cate Mate Electromagnetic Cat Flap has a sensitive, fast reacting circuit in the flap guarantees instant entry for selected pets, even when approaching the flap quickly. These electronic pet doors are operated by one 9 volt battery (not included) so they don't require a location near a wall outlet. A single PP3 (9v) battery will typically give up to 1 year operation. Includes 2 magnets for 2 collars. 4-way lock: 1. Pet has complete access, 2. Out only, 3. In Only, 4. No access.