Features: 100% brand new and high quality Any external pipe cage can be connected as long as the size is the same. Used for blocking the exit, prevent baby escape. Made of high quality plastic, sturdy, long lasting, easy to assemble and take apart for cleaning. Inner diameter: 2.17 inch, great for hamsters, ferrets and rats, guinea pigs and small pet. Specification: Material: Plastic Inner diameter: app. 5.5cm(2.17in) Optional Color: random Quantity: 1 pc Note: Transition: 1cm=10mm=0.39inch No retail package. Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you Package includes: 1 x Hamster Tunnel Plug(other accessories demo in the picture is not included.)