Big Tube Playground Kittens tunnel diameter is 31.5 inches, and the indoor cat donut tunnel tube is 10 inches in diameter. Providing plenty of space for cats or small dogs up to 22 lbs to play. The kitty circle tunnel is very spacious, and small animals can freely go in and out to play and rest, such as bigger cats, kitties, bunny, puppy, ferret etc. 2 in 1 DesignThis donut cat tunnel are splicing design, can be combined as needed when in use, and the shape can become round, semi-circle or S-shape. The middle cushion, comfortable and durable soft mat, provides plenty of room for your cat to rest and play. Premium MaterialCute cat tunnel bed made of high-quality gray plush material that is soft and skin-friendly, warm and breathable. Strong wire structure is very sturdy and ensures the safety of your pet, so your cat can play with confidence. Exquisite Details The two peepholes in this cat cave for indoor cats satisfy the cat's curiosity. In addition, added hanging small ball at the entrance attracts cats, pets to jump and chase brings hours of fun. And exercising every day is good for pets and keeps them healthy. Collapsible Tunnel for Pet The large cat tunnel can be divided into three parts for easy cleaning and store. Besides, adult cat tunnels tube is collapsible and can be folded up in seconds. Take it with you when you go out so your pet doesn't get bored during the trip.