Stainless steel rotors in both machined and mirror polished finished. 84-Up part numbers include reducer spacer for 84-99 applications. Rotors work with all styles of brake pads including Sintered. Surface induction hardened with 12-14% more chrome for superior wear characteristics. Made from 420 stainless steel and precision ground for trueness. Drilled for better wet weather braking and heat dissipation.