Wilwood Engineering Polished Aluminum Duel Master Cylinder. This master cylinder features Polished aluminum finish with black anodized machined aluminum top. Master cylinder has a 1 bore and includes ports on both sides to work with all applications. Master cylinder outlets are 1/2-20 UNF and come with adapter fitting for 3/8-24 and 9/16-20. Master cylinder works with both disk/drum or disk/disk applications just change proportioning valve to match your set up. We also offer proportioning valves, boosters, brackets and brake lines. We will be glad to assist you any way we can. Our goal is to provide you with the best service possible. If, for some reason you do not feel you have received a "5 star" service, please contact a customer service representative.