S&S Cycle SS900-4065A Roller Rocker Arm Kit for Big Twin 84-17/Sportster 86-21Fits 1984 '18 HD big twin engines, 1986 '19 HD Sportster models, and 1994 '02 Buell. Our forged steel roller rocker arms were designed for superior strength and to eliminate the failure prone stress areas found in some other rockers. S&S roller rockers are forged from 8620 steel, heat treated, and then shot peened for additional strength and protection from fatigue. Our rockers also utilize 3 4" long bronze bushings, compared to the more common 1 2"