JEGS Rapid Adjust Timing Chain Set allows you advance or retard your timing 6° without having to remove your valve covers or having to back off your rocker arms. Exact Radial run out tolerance insures your timing adjustments are accurate. Features a billet cam and crank sprocket. The crank sprocket is also heat treated for additional strength. Heavy-Duty roller chain and one-piece roller thrust bearing assembly insure smooth operation.