Progressively wound spring gives a nice, plush ride over the little stuff and won’t bottom out over the big stuff. The more it’s compressed, the greater the resistance. Cold-wound on precision CNC equipment for the ultimate in strength. Heat-tempered, shot-peened and end-ground for durability. Preset for fatigue resistance. Wide variety of rates and applications. Accurate rates and proper fitment. Works with any White Power 5018 shock. Available in white. Made in the U.S.A..