cat door indoor cat door easy to follow instructions pet cat hallway door tunnel feature: Big Cats: Own a bigger kitten like Maine Coon, Burmese, Egyptian? This cat door will fit most cats. The safest cat door you can find: Most cat pet doors are secured with flimsy tape. But this kitty door is securely fastened with sturdy screws. Installs in minutes; fits snugly in place. Keep Bigger Dogs Outside: This big cat door will keep your big dog from eating cat food and litter. No annoying flaps: Ever try to train a cat to use a flap-covered pet door? It’s a frustrating exercise. Luckily, our cat doors are 100% flapless, so your pudgy cat can walk right through. Fits Solid and Hollow Doors: Unlike most large cat doors, our cat doors fit interior doors. Unique design prevents cat paws from getting stuck in the hollow door. Specification: Material: ABS plastic Frame size: height 22.5cm width 27cm thickness 5.5cm Inner frame size: inner diameter 17.5cm inner groove thickness 3.5cm Package