I bought a flap door for a window for the kittens to use to go out to the porch for fresh air and entertainment while I am at work. Tonight when I came home, sure enough, they had learned how to use it while I was at work, and now use it like a super highway! Gosh, I have such smart kitties, if I must say so myself. I think it will keep them happy all winter - especially on the sunny, cold days! It was rather easy to install, although a tad expensive. I highly recommend the door.