Competition Cams 1442-KIT 1.6 ratio, 3/8" Stud Diameter, Magnum Roller Rocker Arm Kit for Oldsmobile 455c.i. V8 Engines Kit includes Magnum Rockers, High Energy Pushrods, Rocker Arm Studs and Guide Plates Constructed from 8620 chromemoly steel, a superior material that will not flex and assures maximum lift Roller tip reduces friction while stiff design and superior ratio accuracy yields more effective valve lift 15 to 30 horsepower increase over stock rocker arms Use in any applications with less than 350 lbs. open spring pressure