Rear Right. Drilled. Machined from billet stainless steel with a center carrier of 7075 billet aluminum in a polished finish. Mounting hole diameter and 3/8". Center hole 56.3mm I.D. for 00-up H-D models. Note: 8-1/2" diameter brake rotors are designed for custom applications. They will not provide the brake efficiency of a stock 11-1/2" diameter brake rotor. All K-Tech 8-1/2" rotors are designed to work with K-Tech 2 and 4-piston calipers or PM 2-p calipers only.