Wiseco (PK1861) 80.00mm Bore 10.2:1 Compression 4-Stroke Piston Kit Fits: Polaris Sportsman 800 2005-12, Ranger RZR 800 2007-12; Piston kit with Top-End Gasket Kit 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 Complete top end gasket kit gives you everything you need to complete your rebuild from premium materials