Safe & Environmentally Friendly Materials: Our hamster exercise ball is made of brand-new PC material. With the lock design, it is easy to install, so convenient and fast!Hollowed-out & Breathable Running Ball: There are multiple vent holes on the ball, which is safe and breathable, and your small pets can play in it! Holes design on both sides of the running wheel which make it more breathable and allow hamsters to aerobic exercise.Transparent & Fashionable Ball: Pets can play in the transparent and large hamster ball, and the owner can observe the pet's every move. So cute!Easy to Install: Adopt the lock design, it can be molded with a light press, easy to install! Please correspond the concave convex to install the clips.DIY a Special Toy for Your Pets: This small hamster ball can be connected to external hamster tubes, and with unlimited extension, which allowing you to DIY combinations to increase the difficulty of exercise for pets!