The Edelbrock Performer-Link True Rolling Timing Chain Sets utilize a solid-bushing chain that rolls with the sprocket on a true bearing surface that eliminates chain stretch. The crank gears are machined from billet SAE-1144 steel which is induction heat-treated. The cam sprockets are made from 35, 000 PSI tensile strength cast iron. Most sets have three keyways to ensure accurate timing for early or late-model vehicles and to allow you to set cam timing 4 degrees advanced, 4 degrees retarded or stock. However, 50-state (stock replacement) sets have single keyways. The Performer-Link timing sets are not for use above 6, 500 RPM.