This spring kit gives a substantial improvement in ride quality while improving handling as well at G-out resistance. We've found the perfect combination of spring length to rate ratio and are very happy with our results. This kit is for all four corners of the machine. After a lot of testing, it was determined there is no need for a dual-rate spring setup on the front of a RZR 900 XC. We decided to stay with the proven single rate spring setup we've been using for years on the fronts of the narrower RZR's. The rear however has found large improvements by switching to a dual-rate combination. These springs are replacements for the OEM springs on the OEM Fox shocks. We provide a short spring, a long spring and a delrin spacer for each rear shock. The secret is in our short springs. We've found a perfect rate which allows us to custom tailor our long springs, (which determines the final rate of the suspension) to each individuals needs.