"The PetSafe 4-Way Locking Microchip Entry Cat Door is the best overall cat flap that’ll keep your cat safe while keeping other animals out of your house. It works by scanning your cat’s microchip and can store up to 40 different microchip numbers. It has a 4-way locking system that allows you to keep the door unlocked or locked, and you can also configure it to allow entries or exits only" according to Catster review in 2024.