These V8 aluminum roller rocker arms (set of 16) with Chevrolet Bow Tie logos, have a ratio of 1.7:1 and stud size 7/16". Main body has exclusive multiplication feature, is CNC machined from extruded aluminum alloy, with pushrod seat of 8620 steel. Bearings and fulcrum assembly are lubricated with pressurized oil, and fulcrum axle and bearings have extra-wide design for load distribution. Roller tip axle is made from 4130 steel, and the roller tip is machined and ground from 8620 steel. Roller and valve stem tips have constant oil supple with reduced friction. Slotted main body is designed to provide extra rocker arm stud clearance; needle bearing fulcrum reduces friction and adds HP over stock pivot ball rockers. Rocker arm nuts are included in this package. Technical Note: These roller rocker arms can not be used with production height steel or aluminum rocker covers.