CSI High Performance Racing Springs are manufactured using the highest quality materials and processes. All CSI springs are pre set and shot peened for high strength, consistency and long life. Shot peening is primarily used to increase fatigue strength life by impacting the surface of the spring with small shot of uniform media with force sufficient to create plastic deformation. Shot peening is a crucial process in manufacturing racing springs and is a highly used process for high performance springs and parts in the racing industry, including F1, Indy Car, NASCAR and NHRA. All CSI High Performance Racing Springs are powder coated Black and are clearly marked with the free spring length of the spring and spring rate for quick and easy identification. CSI High Performance Racing Springs are available for Mugen, Kyosho and Associated. They can be used on both stock shock kits and CSI Pro Clicker Series shocks. Note: These springs are equivalent in spring rate to Kyosho Light Blue springs.