1990-1994 Polaris 350L Trail Boss/2x4/4x4/6x6 ATV Engine Piston Kit [Bore Size (mm): 81.45] Bore Size (mm): 81.45 Piston Kits Include Piston, Piston Rings, Pin and Circlip High Silicone Content for Additional Strength All Namura Pistons have Molybdenium/Teflon Skirt Coatings that Minimize Resistance and Wear to Provide Extended Life Compatibility: 1990-1994 Polaris 350L Trail Boss/2x4/4x4/6x6