Rainbow Run-about Balls have been a favorite pastime for years, providing pets and pet owners with interactive fun during playtime. Sized perfectly for hamsters and gerbils, these colorful Run-about Balls provide the perfect outlet for your pet's excess energy. Available in four colors, Rainbow Run-about balls are a cool 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.7 Diameter - UPC: 45125613537