Reduction
rings are used to "fine tune" your pump and impeller
combination. The rings are available in both smaller
and larger diameters to help extract that last bit
of acceleration and top speed. We find the rings work
well to "fine tune" the pump in different water conditions.
For example, you might want the larger ring for better
acceleration in surf conditions, where the smaller
ring will possibly increase your top speed on flat
water or high speed courses.