Rotors are surface Induction Hardened with 12-14% chrome content for superior wear characteristics on A1S1 420 Stainless Steel plate Rotors are precision ground for trueness and machine-punched for accurate mounting holes The drilled full-sweep pattern provides superior heat dissipation and consistent wet or dry performance Available with satin or highly-polished finishes for a great custom look 11-1/2" diameter, Counterbored mounting holes, uses stock hardware or 240-704 or 240-703 chrome-plated buttonhead screw