Husky Spring Variable Rate Coil Springs provide greater load support without causing a harsh ride. They have 2 zones with with different pitches or angles. The top, more horizontal coils compress easily for comfortable ride quality. After load or a jounce has completely compressed the Comfort Zone part of the spring, the Load Zone with it's greater pitch and greater spring rate becomes more active. The variable rate spring automatically gives the appropriate load support due to it's unique variable pitch design.