Give your pet a door that's just their size! The PetSafe Wall Entry Pet Door gives your cats and dogs freedom to go in or out without asking for your help to open the doorperfect for potty breaks or play time. This door is great for homes where installation in a door might not be possible. The included telescoping tunnel allows you to install the pet door into all types of interior and exterior walls. If you are installing the pet door into a thicker wall, you can purchase a compatible extension kit for the telescoping tunnel. Use the closing panel to control when your pet comes and goes. This pet door is available in 3 sizes so you can find the best fit for your best friend. Your pet deserves the best. Trust PetSafe to help keep your pet healthy, safe and happy. Best option for homes where door installation isnt possible Install into interior and exterior walls 4 3/4 in - 7 1/4 in thick Purchase a compatible extension kit to install door in walls thicker than 7 1/4 in Give your dog or cat freedom to come and go without asking for help Closing panel to control your pets access Energy efficient pet door Small size for cats or dogs up to 15 lb; flap opening measures 5 1/4 in W x 8 1/8 in H Medium size for dogs up to 40 lb; flap opening measures 8 1/4 in W x 12 1/4 in H Large size for big dogs up to 100 lb; flap opening measures 10 1/4 in W x 16 1/4 in H