Wiseco PK1645 99.20 mm 12.5 Piston domes are designed for optimal quench during the compression / combustion cycle, resulting in resistance to detonation and pre-ignition; the end product is longer engine life and increased horsepower potential Each piston is built from race proven designs that are chosen by the top race teams in all forms of racing including super cross, motocross, GNCC, superbike, and more Resistance to impact and fatigue