About this item: - Superior Insulation: Our dog door features an additional insulation flap between two outer flaps, effectively blocking cold air and retaining warmth. Magnetic strips on the flaps and dust strips on the frame ensure a tight seal, keeping out dust and insects. - Durable All Aluminum Construction: Crafted from high-quality aluminum alloy, this door is exceptionally sturdy, resistant to deformation, rust, and corrosion. The paint finish is long-lasting and won't flake off. - Perfect for Large Pets: With a spacious 18.7 x 9.92 inch flap opening, it accommodates dogs and cats up to 110 lbs. The adjustable tunnel fits doors or walls with thicknesses from 1.26 to 2.08 inches. - Enhanced Security: A sliding closing panel and robust aluminum lock allow you to secure the door when needed, preventing unauthorized outdoor access. The lock is built to last. - Easy Installation: Comes with a detailed manual and video guide. Before installing, verify that your door or wall thickness matches the product specifications. No special tools required. - Versatile Use: Suitable for various door types and walls, providing a convenient passage for your pets while maintaining energy efficiency and home security.