【Environmentally friendly materials】: We have selected high-quality plastic materials which are environmentally friendly, so that we can protect pets’ health well. 【Hollow runner】: The hollow design on one side of the running wheel makes the running wheel more breathable and allows hamsters to exercise more and maintain good health. 【Non-slip patterns】: Non-slip patterns inside the running wheel, make this running wheel effectively prevent your hamster from slipping due to inertia while running. 【Seamless Running Wheel 】: There is no gap in the racing wheel, it is suitable for preventing hamsters from pinching their feet when racing in the wheel. 【Quiet toy】: This silent toy allows your pet to have a good nighttime fun and enjoy a happy life!