Racing Rotor, for MSD and GM Distributors with Window CapsThese Hi-performance Racing Rotors are specifically designed for high RPM and endurance which is standard on most MSD Pro-Billet Distributors. Rotors are injection molded from Rynite material for incredible strength and high dielectric properties. Plus the stainless steel/brass rotor tip is screwed in place to handle extreme RPM and heat conditions. The rotors feature deep molded vanes to cause air turbulence inside the cap which prevents spark ionization and carbon tracking.Will not fit MSD 8485 and MSD 8473 Distributors.