Allows for the use of 2.5" ID springs on the standard 2.25" ID spring perches.  Sold as a four piece kit and 
completes one pair of shocks or one coil over kit.  These will work on all of our RSR coil over kits but most popular for the 914 since they have much more room to accommodate the larger 2.5" springs.  The 2.5" ID springs suit the 914 very well, being available in lighter spring rates (less than 200 lbs/in) often complimenting the 914 owner that wants to maintain street comfort while adding a significant performance gain.