Pair of XX-long progressive-rate springs are custom-wound to provide responsive control over small bumps, with a progressively stiffer rate to absorb hard landings. Progressive springs are offered in different rates to tune your suspension performance or compensate for lighter or heavier vehicle configurations. Rates are relative to stock spring rates. (+20% rate, blue stripe) Fits XX-long Ultra Shocks or Big Bore shocks using 3768 spring retainers. Does not fit GTR shocks.