Alfie Pet by Petoga Couture - Keith Exercise Running Track for Mouse, Chinchilla, Rat, Gerbil and Dwarf Hamster The track measures 7.25" wide and 24" in diameter. The ball is 5.25" wide. Ideal for hamster, mouse and other small furry animals. This is a fun way to exercise your small animal pets; relieves boredom and increases activity level. They will love it and be entertained for hours. The ball is made from shatter-resistant plastic, great ventilation, and screwed together segments for durability. Easy to assemble and clean.