Proform 66906B Stamped Roller-Tip Rocker Arm, 1.5 Ratio, 3/8" Stud Designed for select Chevrolet Small Block Engines 1.5 Ratio for 3/8" studs Extra long slot eliminates rocker to stud interference. Reduces internal valve train friction 16 rockers, anti-gall grooved balls and nuts per package