The Hoops Gear Set is a gear set that is a collection of nested rings. It provides a selection of the largest rings that can be fit onto a small gear set.
In the picture for the hoops set you can see that there are lots of sizes of rings available but also that each ring is narrow so it can be used a a third piece between a big ring and a gear, this use makes new designs possible that cannot be achieved any other way.
The gear/ring combinations in the hoops set are:
176, 176/160, 160/144, 144/128, 128/112, 112/96, 96/80, 80/64, 64/48, 48/32, 32/16, 16