Wiseco (SK1321) 77.25mm 2-Stroke Piston Kit for Polaris Snowmobile 2-stroke kits feature our Pro-Lite pistons that are CNC machined for optimal cam shape and profile for peak horse power and service life; kit comes with top-end gasket kit Dedicated forgings used for superior strength to weight ratio utilizing aerospace alloy High performance ring kit and alloy pin included with each piston kit for extended life and sustained power Each piston is built from race proven designs that are chosen by the top race teams in all forms of racing including snocross High quality parts specifically chosen by Wiseco to match their forged pistons are included in this kit for easy one stop shopping