2000-2002 Polaris Trailboss/Magnum/Xpedition 325 ATV Engine Piston Ring Kit [Bore Size (mm): 77.95 (Stock)] Bore Size (mm): 77.95 Ring Kits Include Piston Rings Only - Piston Not Included Namura Piston Rings Fit Both Namura and OEM Pistons of the Same Bore Size Unless Otherwise Specified Compatibility: 2000-2002 Polaris Trailboss/Magnum/Xpedition 325