Light weight and small size. Portable. Encourage safe healthy exercise. Suitable for hamsters, gerbils or other small animals. Interactive fun for pets and pet owners. Serves as a makeshift waiting area for your four-legged friends while you clean the house. The method of installing the cover at both ends of the racing ball: the cover is designed with a hidden buckle. When installing, the buckle position of the cover is aligned with the corresponding position of the running ball, and the cover needs to be twisted. until it's screwed all the way.