Rocker Arm, Magnum, 3/8 in Stud Mount, 1.52 Ratio, Roller Tip, Chromoly, Small Block Chevy, Set of 16. Magnum roller rocker have a lower-friction roller tip to reduce valve tip and guide wear. The stiffer cross section prevents flex and increase valve lift good for 15 -20 hp. Please e-mail with questions.