The Endura Flap Pet Door’s award winning design makes it the most energy efficient pet door line on the market. Made with machined aluminum and the industry exclusive Endura Flap pet door. Each wall mount model has a tunnel that fits walls between 2 and 8 inches thick. Flaps are sealed with adjustable magnets for wind resistance. Flexible in temperatures 40 degrees below zero. There’s a perfect door for any size pet. You can give your pet freedom while keeping your home insulated and secure.