Features: Made of high quality plastic, non toxic and safe. Simple and convenient to assemble, is a good toy for mouse play and exercise. Running can relieve hamsters' anxiety and stress, making them rest assured. Let the mouse go to "play". Ball diameter is about 3.94 inches. Suitable for dwarf hamsters, mini gerbils, baby squirrels, junior hedgehogs, and other small pets. Reinforced structure, durable, and not easy to break. Multiple Venting hole design providing good ventilation. Detachable cover design, no need worry about small pets falling out. Easy to clean. We offer 4 colors Blue, Red, Yellow, and Transparent. Specifications: Material: Plastic Color: Blue/Red/Yellow/Transparent Size: Diameter Approx.10cm/3.94in Weight: Approx.48g Package Includes: 1 Piece Hamster Running Ball Toy (Blue/Red/Yellow/Transparent) note: 1.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!