Kit includes S&S 1250cc pistons with rings and wristpins, S&S 3-9/16" bore cylinders, MLS head, base and exhaust gaskets, assembly lube and instructions. Forged pistons have larger than stock valve pockets and accepts up to 2.00" valves. Forged pistons - coated piston skirts with measurement window and S&S logo. Made in the U.S.A.. 883 models will require the use of XL1200 cylinder heads to achieve correct compression ratios.. Will not work with XR1200 models..