ULTIMATE INDEPENDENCE: Get complete control of your pet& 39;s movements. Specially developed for large cats or small dogs up to a shoulder height of 360mm. Self-lining to 50mm thick - perfect for all doors and thin panels. Wall liners available separately to extend the tunnel as necessary FLEXIBLE 4-WAY LOCK: The secure double point 4-way locking system gives you the option to set this pet door to in only, out only, in or out or fully locked LOW NOISE DOORS: This large pet flap has brush strips at the edges of the door to help reduce the noise created by pets when they enter or leave the door. The silent movement of the flap won& 39;t frighten your pet or disturb you as the owner HIGH-QUALITY DESIGN: The brush sealed, magnetically closed flaps are draft and weather resistant. The large transparent flap allows your cat or dog to see through the door, which is preferred by most pets. The product dimensions are 235 mm wide x 252 mm high. WALL LINERS AVAILABLE: If you need more length when installing your pet flap, you can purchase the Closer Pets CP400W Large Pet Flap Wall Liner separately (50 mm (2 Inch) each)