Bore: 101.47mm Compression: 9.2:1 Compression Sizing: 1.50mm OversizeTop End kit includes: piston, rings, wrist pin, clips, top end bearing, and gasket kit. MOS2 (made with Teflon/Molybdenum) Coated Skirts A rolled on application process provides a fits Bond that is 10 times stronger than other spray on coatings. Benefits include increased heat transfer, reduced friction and helping to eliminate cold seizures. Machined Smooth Heads Reflects combustion heat and reduces carbon buildup, protecting the top of the piston. Some tests have shown this feature can increase horsepower and fuel economy by up to 6%. Anodized Domes Increases heat resistance and durability; pistons with anodized domes are 75% stronger than non-anodized pistons. Hypereutectic Casting Process Provides higher silicon content for reduced expansion rates and additional wear resistance; it also has an ability to withstand higher cylinder temperatures.2002-2007 fits YAM YFM660F Grizzly 4x4 2004-2007 fits YAM YXR66F Rhino 660 2007 fits YAM YXR66F Rhino 660 Ducks Unlimited 2006-2007 fits YAM YXR66F Rhino 660 Exploring Edition 2006-2007 fits YAM YXR66F Rhino 660 Special Edition 2007 fits YAM YXR66F Rhino 660 Sport Edition