Hamster balls

Hamster balls are hollow spheres made of clear plastic into which hamsters, gerbils, degus and other small rodent pets are placed, allowing them to run around outside their cages without the risk of running away, getting lost under furniture or in walls.^[1] The balls also produce an audible rumble across many surfaces, making the hamster easier to find.

Most hamster balls 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.^[2] Hamster balls are supposed to provide exercise for hamsters.^[3]

Although hamster balls are designed to protect hamsters, there are hazards such as stairs and other high places from which hamsters can fall, resulting in injury or even death. So in order to protect the hamsters, the owners place hamster balls on the lower level of their house, away from any stairs.^[4] Some also create a simple barrier near the stairs, so that they will not roll down the stairs.

Although hamster balls have air holes, hamsters should be allowed to take breaks and leave the ball regularly due to a lack of water that could potentially induce heatstroke or exhaustion.

Hamster and other small pet owners should also be advised that it is important to keep watch over the hamster ball at all times while the pet is inside.^[1] Some hamster owners have noted that at times the ball can pick up too much speed, causing the hamster to somersault inside and potentially be injured.

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

http://en.wikipedia.org/wiki/Hamster_ball