Give your cat easy access through any interior door with the PetSafe Cat Flap. This means, for instance, you can keep the cat’s smelly litter box in a room shut off from the rest of the house behind a closed door. The high-impact white plastic device includes a transparent flap and fits any interior door between 1 and 2 inches thick. A sliding lock lets you bar access to the flap if you choose. For cats up to 15 pounds. Some assembly required. For interior use only. Measures 5.75 inches square.