Hamster ball

[3] Most are made of durable transparent plastic with air holes and a small door or lid to allow the owner to insert or remove the hamster from the ball.

Hamster balls are recommended by the manufacturers for use with hamsters, gerbils, mice, degus and small rats only; they should not be used for chinchillas or guinea pigs, as their size and body structures are different from small rodents, posing a serious hazard to them if placed inside.

[6] The Tierärztliche Vereinigung für Tierschutz [de] (TVT), the German veterinary association for animal welfare, warns that hamster balls pose a risk of injury.

TVT warns of a risk for injury when the ball hits a wall or rolls down from raised surfaces, and deems the small ventilation slots to provide insufficient air supply for the hamster.

TVT considers hamster balls to be anti animal welfare and do not recommend their use for any small mammal.