These COMP Cams Ultra-Gold Aluminum Roller Rocker Arms with a 3/8" stud diameter and 1.5 ratio are designed for Chevrolet V8 265-400 applications. The new modern design features of these Ultra-Gold Rockers are proven to withstand extremely aggressive spring pressure and valve lift. Designed specifically for high performance street and race engines, the Ultra-Gold Aluminum Rocker Arms are precision CNC-machined to strict tolerances. Developed to meet the demands of professional engine builders, these rockers include features never before possible in an aluminum rocker arm.