Good way to let your cat in but keep other cats out. If your cat has been microchipped, this door can be taught to recognize it and let *only* that cat in. Able to recognize multiple cats. Can be set to "closed", "in only" and "in/out". Intended for indoor/outdoor use. I had this installed in a closet door (also available) to keep one of two cats out of the other's litter box. Later I made a simple door frame (not available) and installed the closet door between the house and my room, so my cat had time away from the other cat. You're welcome to the closet door, too, if you want. For product information check out https://www.surepetcare.com/en-ca/pet-doors/microchip-cat-flap