Size: 4.7 inches, enough room for a hamster to run around. Environmental friendly and safe material: Made of eco-friendly resin, transparent, durable and non-toxic. Easy to clean, the entire ball can be washed down with water. Encourage healthy exercise in a safe and secure way It’s a great temporary storage area while you clean your friends house fur Not suitable for ferrets, guinea pigs and rabbits Hamster exercise ball, small animal hamster toy running exercise jogging , transparent hamster activity ball for mice