Armor Flex pet doors feature a revolutionary patent pending flap design that creates an air tight seal, providing the highest level of extreme weather resistance and energy efficiency. The innovative new flap design is made of individual, interlocking segments, each and every precisely located by rare earth magnets. The interlocking segments pivot relative to each other to give you the horizontal rigidity required to create and air tight seal whilst providing vertical flexibility making it easy and secure for your pet to use. These extremely prime quality pet doors feature heavy duty aluminum frame construction, high strength ABS composite flap construction and all stainless steel hardware. The doors are finished with the toughest industrial powder coat to look beautiful and work perfectly for years and years. In comparison to other pet doors available on the market, new Armor Flex doors represent a big step forward in quality, innovation and technology with lower pricing to provide you with not just a great pet door but a great value. The AF2-XLW is Extra Large Size and Wall Installation. Includes Wall Tunnel.