Fits Chevy small block engines w/ center hold-down valve covers. Rid your engine of internal friction with roller-tipped rocker arms. The race-proven full needle bearing, fulcrum and roller tip not only unleash horsepower, they also lengthen valve train component life and reduce wear and tear on valve stem tips. Precision machined to insure consistency and ratio accuracy. 16 extruded aluminum roller rockers and 16 poly locks.