Wodent Wheel 8 Inch, Black with Blue Track Wodent Wheels are easily disassembled for cleaning and are constructed of tough, safe plastic with a stable base of heavy-gauge painted (baked-on powder coated) steel. Wodent Wheels are much safer and quieter than conventional wire exercise wheels, and have a clean, simple design using recycled and recyclable plastics. Rodents are attracted to the wheel's entry holes which also offer a really nifty effect when watching them run. Hamsters avoid broken legs and strangulations. NOT RECOMMEND for sugar gliders (their tails can get damaged by the center axle). The semi-enclosed design and the solid rear wall also makes rodents, who are natural 'wall-huggers,' feel much safer as they run. Approved by the ASPCA.