1、Fitment: Piston cylinder top end kit is replacement for Polaris ATP 500 2004‑2005, replacement for Polaris Big‑Boss 500 1998, replacement for Polaris Magnum 425 1999. 2、OE Number: The referencing OE number of the kit are 3089966, 3089256, 3087224, 3087221, 3087170, 3086813, 3086811, 3086493, 3086448, 3086447, 3086200, 3085866, 3085635, 3085634 etc. 3、High Performance: The cylinder can improve engine displacement and performance and increase horsepower and torque, which can reduce engine shake and make driving more stable and smooth. 4、Principle Information: A piston is a cylindrical engine component that slides back and forth in the cylinder bore by forces produced during the combustion process. 5、Piston Function: In an engine, the piston purpose is to transfer force from expanding gas in the cylinder to the crankshaft through a piston rod and or connecting rod.