Review on PetSafe Microchip Cat Door, RFID Multi-User Access for up to 40 Pets, 4-Way Locking, Weatherproof, Easy Install, With Hardware Kit - Ideal for Cat Litter Box or Pet Feeder Privacy. by Chere Reiners

This cat flap makes a loud, repetitive, annoying click each time the button is pressed or pushed back up, blocking the movement of the cat flap. When the cats sit next to him, their microchip will trigger the button, and he will press and rise again continuously and loudly. This sound seems to startle the cats enough that they can't get through the valve, but not enough to scare them away, so they just stick their head in the valve and let it click over and over again. It's very annoying and a lot louder than you think, especially when they try to leave at 3am. Adding to this annoyance, my cat can pick the lock. When it's set to 'In Only', she can press the button down with one paw and hook her claw under the cat valve, pulling it in and sliding out under it. Now I'm looking for a quieter and more reliable cat damper. UPDATE: As I mentioned, our cat can flip the valve and run away when it's set to 'In Only', but her tail got stuck in it and she damaged it so badly we almost had to amputate it. Vet bill: $200 and sad, painful times for a kitten.