Stainless steel with black carrier and black nitrided disc. 11.8" / 300mm OD.; 56.3mm I.D.; 8.5mm (5/16") counterbored mounting holes with 3.25" bolt circle hole. 5mm thick. Fits OEM or accessory cast & laced wheels with 3.25" bolt circle mount holes. Mount style ''B''. Repl. 46717-10. Designed by Master Designer Kodlin; produced by Brake Specialist SBS. It is just logical that when combining specialists in their respective fields you get the best of both worlds; and that is exactly what happened. Made of a high quality stainless steel; alloyed with a high carbon content; to offer excellent brake performance and reliable stopping power in any condition. Note: Only the friction area of the black nitrided outer stainless disc will wear away quickly; leaving the rest of the disc black.