10.25:1 Compression Ratio. Bore Oversize +3.50mm. 4-stroke. Non-coated. Complete piston kit includes pistons, rings, wrist pins, circlips and top-end gasket kit for one complete engine. Optimized compression ratio to fit your build and performance goals. Designed and built specifically for each V-Twin engine platform. Improved tensile strength of forged material optimizes strength and service life. Engineered, forged, and machined in the USA. Wiseco ring types are not interchangeable (i.e., CD is not interchangeable with LC). Wiseco pistons can be fitted only with Wiseco rings. Cylinder sleeves must be purchased separately.