COMP Cams Magnum Roller Rocker CS 1.52173 Applications is the ultimate street Rocker. With a 10mm Stud diameter and 1. 52 ratio, it is designed for Serious performance enthusiasts. All Magnum Roller Rocker Arms are constructed from 8620 chromemoly Steel, which is a superior material that will not flex and assures maximum lift. Their Roller tip reduces friction, while stiff design and superior ratio accuracy yield more effective valve lift. With a 15 to 30 horsepower increase over other