The Performance Quotient PQXaluminum rocker arms are made from 6061-T6 or Series 7000 2024 aircraft quality aluminum alloy extrusions. Each rocker body is relieved for extra valve spring clearance and anodized for added strength. CNC machined billet steel pedestals, ground steel alloy rocker shafts, PRW SCM-4135 alloy steel SHOP NOW/Fasteners, Studs & Bolts, and needle roller bearings from the finest manufacturers in the world comprise the foundation of these rocker arm systems. These complete kits include all the components and hardware required for a professional installation.