The FAST HEI Cap and Rotor Service Kit is a high-quality upgrade for GM HEI distributors. The kit includes a cap coil cover and two different rotor buttons. The black cap and coil cover are injection molded with Rynite for ultimate performance durability and protection from ignition arc-through. Brass and stainless terminals and contacts provide superior corrosion resistance and maximum spark energy distribution. Two different rotor buttons are included to use with either stock HEI or CD ignitions. The high-resistance carbon rotor bushing for use with stock HEI distributors helps suppress radio frequency interference. However when the high voltage of a performance CDI is added resistance may build excessive heat damaging the distributor cap and rotor. The low-resistance rotor bushing allows the secondary voltage to be directed away from the distributor cap to the rotor without excessive heat buildup.