Perfect Size for Most Fences: Our dog fence window has an outer diameter of 12.4 inches, an inner diameter of 10.1 inches, and a depth of 4.9 inches. Simply cut a circular hole in your fence according to the inner diameter for a precise fit. Suitable for most wooden and vinyl (PVC) panel fences, but not recommended for iron or chain-link fences. Comfortable Air Hole Design: Equipped with 8 small air holes, the clear dome ensures proper ventilation while giving pets a more enjoyable viewing experience. Your dog can watch the outside world comfortably without feeling stuffy. Quick & Secure Installation: Comes with safe screw accessories for worry-free setup. Just measure the screw length, fence thickness, and window size carefully, and you can easily install a durable porthole that brings fresh air and curiosity to your pet. Keeps Pets Happy: The transparent window satisfies your dog’s natural curiosity, reducing boredom and anxiety. Even when you’re not at home, your furry friend can watch the outside world and stay entertained. Multi-Purpose Design: Beyond fences, this pet window can also be used in dog houses, cat trees, or indoor play areas—making it a fun and versatile addition for both dogs and cats. The transparent dog window allows the dog to see the world outside the fence anytime and anywhere, so that your friend can feel happy when you are not at home.