The award winning Endura Flap wall mount pet door is the most energy efficient wall mount on the market. It also is highly wind-resistant, has completely hidden hardware, has beefy aluminum extruded framing, is thoroughly built to last and backed by a superior 10 year warranty, with 15 years on the flap. Included is a sturdy locking cover, equivalent to 1/16" sheet of steel, with an easy to use clip lock so you can close off the door when not in use. It is also 100% designed, engineered and manufactured in the USA. The tunnel section will frame out walls up to 8" in thickness. While the single flap version insulates exceptionally well, the double flap version is a great option for very harsh climates.