Moon glow run-about balls provide pets and pet owners with interactive fun during playtime. Sized perfectly for hamsters and gerbils, the glowing run-about ball provides the perfect outlet for your pet"s excess energy. Our glow-in-the-dark moon glow run-about balls also make a perfect temporary area to keep your furry friend while you are cleaning their cage. For added safety, use your run-about ball on super pet"s hamtrac raceway and provide your pet with a controlled exercise environment.