DURABLE & WEATHER RESISTANT: the Endura Flap double flap pet door is designed with a high-quality aluminum frame and an insulated flap that remains flexible in extreme temperatures, providing excellent weather resistance and energy efficiency for your home; medium flap measure 8" x 14" and is suitable for pets up to 21" tall VERSATILE INSTALLATION: our pet door is suitable for a wide range of doors, including solid core, hollow core, metal, and storm doors, and is available in four sizes to accommodate pets of all sizes; pet door is designed to fit doors between 1-5/8" to 2-3/8" thick EASY INSTALLATION & SECURE LOCKING: The pet door comes with easy-to-follow instructions and a heavy-duty locking cover, strong as 1/16" steel sheet, ensuring secure closure when not in use; ideal for interior and exterior door installations ADAPTABLE TO YOUR PET'S NEEDS: the three-sided magnet design of the Endura Flap pet door is adjustable for training timid pets, while providing the strength you need to keep the wind out; flaps are rated to stay shut in gusts of up to 50 mph BUILT FOR LIFE: our pet doors are manufactured in the USA with quality construction and backed by a lifetime warranty; invest in a reliable, long-lasting pet door that will serve your pet's needs for years to come The Endura Flap Pet Door offers a reliable solution for pet owners seeking to provide their pets with easy access in and out of the house. Designed for superior insulation, it keeps your home comfortable while saving on energy costs. The flexible flap material remains functional in extreme temperatures as low as -40 degrees Fahrenheit. This flap is suitable for small and large pets. Built with a sturdy aluminum frame for added strength and versatility, the pet door is designed to withstand daily use by pets of all sizes. Available in white, black, or tan aluminum frames, the pet door is designed to match your home’s décor. The new E2 design combines stylish modern aesthetics with the established durability and performance of Endura Flap. It includes a robust locking cover, providing added security for your home. The triple-sided magnet design in the flap allows for flexibility when training pets or accommodating timid pets. Proudly designed, engineered, and manufactured in the United States, the Endura Flap pet door comes with a lifetime warranty, ensuring long-lasting use and reliability.