Known for their phenomenal spring ride performance, Skyjacker's precision engineering gives you all the vigorous off-road handling needed while providing the smooth street riding characteristics that you demand. Skyjacker specifically engineered a progressive variable rate coil spring, distinctively a 2-stage dual rate long travel coil. Spring rate progression is from a first Flex Rate to a second Ride Rate. First Flex Rate stage of coil spring delivers a comfortable ride with ability to flex / expand during full articulation. This keeps coil springs seated at upper coil mount and tires in contact with terrain. Second Ride Rate stage of coil spring engages after compression past the First Flex Rate. The process starts with SAE9254 spring steel material, an advanced method of shot peening and a presetting process. Each coil spring is blasted (shot peen) with hard steel pellets at very high velocities. Shot peening compresses the surface of the steel thereby increasing the tensile strength of the spring. Compressing the spring completely down to where the coils touch (solid height) is preset. This takes any fatigue or stress off the spring and eliminates sagging. Every coil spring has endured a cycle test to assure the very best in quality. A baked on powder coat provides an extremely durable protective barrier to prevent corrosion.