Avoid wheels made of plastic, as they can be chewed. Plastic pieces on toys may be ingested and cause serious problems. Your wheel should have a solid running surface to avoid feet slipping between bars, causing broken bones. Crossbars can cause major injury, as there is no means for the chinchilla to stop the wheel and jump out. As such, the cross bars can cause an appendage or neck to be caught. Wheels should be at least 15 inches in diameter for adult chins.
With all wheels, be cautious that they are properly placed in the cage to insure that your chin will not accidentally fly out of an open door or become injured. Check the screws often to insure that they have not become loose. Mount wheels in a multiple chin cage to insure that another chin in the cage will not get hit if a chin is running on the wheel.
The Ed Wheels from ChinWorld and the Chin Spins from Quality Cages are affordable alternatives. PNWC wheels are very durable. Flying saucer wheels take more time to put together than the time it takes for most chins to get used to using them.