These rotors are designed with high RPM and performance in mind which is why they are standard on most MSD Pro-Billet distributors. Both rotors are injection molded from Rynite material for incredible strength and high dielectric properties. Plus the stainless steel/brass rotor tip is also screwed in place so it can handle extreme RPM and high heat conditions. The rotors feature deep molded vanes to stir up the air inside the cap to prevent spark ionization. The rotor screws are set deep in the housing to prevent spark scatter.