These forged pistons are designed as an intermediate compression piston for engines with S&S® Super Stock® cylinder heads. These pistons can be used to increase the compression of S&S® Sidewinder® kits for HD® Evolution® engines and in S&S® engines with Super Stock® cylinder heads. They are designed to be used in 4-1/4", 4-1/2", and 4-5/8" stroke engines with stock (8-1/2") diameter flywheels, and in 3-13/16" and 4-3/4" stroke engines with small (8-1/4") diameter flywheels. 3-5/8" bore. Made from high strength low silicon forging for racing applications. *Small Diameter Flywheels. Piston kits include set of pistons, rings, wristpins, and clips.