【Environmentally friendly material】: Hamster running wheels are made of high quality environmentally friendly plastic materials to protect pets’ health. This product uses a new one PC material with lock. It’s easy, convenient and quick to install this product! 【Hollow wheel】: The design that both sides of the wheel are hollow allows hamsters to breathe easily and do aerobic sports. There are multiple reliable air holes in the wheel, your pet can have fun long in the wheel! 【Transparent wheel】: Pets can have fun in the large and transparent hamster racing wheel, and you can watch your pet’s every move, it’s interesting! 【Easy Installation】: With the lock, you just need to press it lightly to assemble this product, it’s easy to install! 【DIY Combination Toy】: This small hamster wheel can be connected to the other tubes, allowing you to create other combinations to increase the game difficulty for your pet! It can be combined with rails and tubes. A variety of combinations allows