Pro HEI distributors feature a more powerful ignition module and coil. The unique ignition module and internal coil are capable of running above 9,000 RPM, while stock ans other performance modules loose spark energy at about 5,500 RPM. The Procomp module produces 50% more current than stock units and delivers a much more precise timing signal as well as dwell control. TIG welded to the top of the shaft is an adjustable mechanical advance assembly which features Chromoly weights for timing advance through the entire RPM range. There is also an adjustable vacuum advance canister to improve economy. All of these features are enclosed in a great looking CNC machined housing for accuracy and strength. Comes complete with a high quality rotor ans cap that has brass terminals.