Replacement springs are an ideal upgrade if you need a bit more stiffness from your ShockStop Suspension Seatpost. The stiffer springs provide a more topped-out feel, or if you're at the upper end of the weight range and want more support. Approximately 25% more stiffness than the standard spring set Includes two steel springs (one outer and one inner spring) Only compatible with the 27.2mm diameter versions of the ShockStop Endurance Seatpost (both the 280 and 350mm lengths)