Environmentally friendly materials: Select high-quality environmentally friendly plastic materials to better protect pets' health. Hollow Runner: The hollow design on one side of the impeller makes the impeller more breathable and allows hamsters to do aerobic exercise. Anti-slip pattern design: Anti-slip pattern design on the inside of the running wheel, which can effectively prevent your hamster from slipping due to inertia when running. Seamless Running Wheel: There is no gap in the main body of the running wheel to prevent hamsters from getting their feet caught when moving. Toy without noise: Pets can play happily even at night. Let your pets enjoy a happy life! Specification: Size: 18*18cm Color: blue The packaging of this product contains: 1 * racing bike