These S&S B2 cylinder heads fit 1999-'16 HD big twin engines with 4-1/8" or larger bore, built with crankcases with the stock cylinder bolt pattern. The perfect upgrade to a late production S&S T-Series complete engine or Long Block, or 124" Hot Set Up Kit. High lift S&S valve springs allow cams of up to .660" lift. CNC ported for maximum air flow and greater performance gains. Black wrinkle powder coat finish. Requires special pistons, pushrods, intake manifold, intake flanges and seals, and an exhaust adaptor kit, sold separately.