Wiseco K2771 3.937" Bore 10:1 Compression Ratio Flat Top Forged Piston Kit Fits: All Harley-Davidson Twin Cam engines 1999-2013 with 4-3/8 inch stroke crank 106 cubic inch (1746 cubic capacity) big bore kit includes 10:1 compression ratio flat top pistons, rings, circlips, chrome piston pins Overbore stock cylinders, or big bore cylinders required, compatible with Screamin' Eagle cylinder heads (starting in 2011) Dedicated forgings are used for superior strength to weight ratio utilizing aerospace alloy with a dome designed for improved flame travel and detailed skirt shape and profiles for stability and smooth operation in the cylinder bore Utilizes the new ArmorGlide skirt coating, the ultimate in toughness, lubrication, and bond technology working together to minimize friction, maximize horsepower, providing improved wear resistance