The 15 inch chin spin or the metal flying saucer. Both are great and you can find both of them on the Quality Cage Company website. They are expensive but they will last a long time, unlike the ones the pet stores sell. You also will not need to worry about the chinchilla chews on wither of these.
I bought one wheel (silent spinner) as a tester before buying a metal wheel, but none of my 5 chinnies have ever used it so i took it out as it was just taking up space
I've had the Silent Spinner since October, I thought it was the best thing since sliced bread until my chinchillas running on it caused a bar on my Critter Nation to snap in half. (They sort of play rough) Now the wheel keeps me up all night. I finally caved and bought the metal Flying Saucer, I hope it doesn't rattle the cage like the spinner did!