Made of plastic material, effectively preventing from biting. Round design makes it more stable and safer. Provide a good temporary holding area for your pet when you clean your pet house. Provides interactive fun for the pet and the pet owner,make your pets fun. With this exercise ball, your small pets will no longer be limited to the small cage, it can effectively increase their activity space. Perfect for dwarf hamsters, sugar gliders, ferret and other small animals. Specification: Material: Plastic Diameter of Ball: Approx. 10cm/3.94 inch Package Includes: 1 Piece Running Ball Note: Since the size above is measured by hand, the size of the actual item could be slightly different from the size above. Due to the lighting effects, monitor settings, etc. There could be someslight difference in the color of the pictures and the actual item.