Super Pet Clear Run-About Ball for Hamsters (Mega, 13 Inch Diameter) The Mega Run About Ball measures 13 inches in diameter and is the BIGGEST ball available anywhere! Now provide larger pets with the same freedom to exercise that smaller pets have enjoyed for years. Bigger pets can now enjoy the world around them inside these colorful, oversized exercise balls. It's an excellent source of exercise for pet rats and chinchillas, plus its a fun roly-poly toy for ferrets and a neat pet carrier for guinea pigs. The Mega Run About Ball also fits perfectly onto Super Pet's Hamtrac Raceway for the safest and most controlled exercise environment. Color specification is unavailible for this item