The In-n-out Pet Door is a different kind of dog door. It saves hundreds of dollars and doesn’t destroy your door-Works on glass doors, French doors and solid doors-Great for small, medium and large dogs-Rugged all metal design is easy to install and remove, it’s portable-Attaches to your door no big hole required- Most secure dog door on the market. Why? Because the dead bolt lock works as normal and there is no big hole for a burglar or snake to crawl through.