Environmentally friendly materials: The hamster gym balls select high-quality environmentally friendly plastic materials to protect pets' health well. It is made of the material of a new piece of PC,With interlock design, easy to install, convenient and fast Hollow channel: The hollow design on both sides of the impeller makes the impeller more breathable and allows hamsters to do aerobic exercise. There are multiple ventilation holes on the ball, which is safe and breathablesmall animals can play for a long time Transparent BallPets can play in the large transparent hamster ball, and the owner can watch the pet's every movement. Very cute Easy to Install: Keyhole design, can be molded with light pressure and easily installed Combination game: This small hamster ball can be connected with outer tubes and unlimited extension, which can make DIY combinations increase the difficulty of pets