Proflow's oval-shaped, dual bowl master cylinders are made out of aluminum with 3 3/8 in. center-to-center mounting holes, 9/16" & 1/2" ports on the Left side and can be paired with our Proporting Valve Kits for Disc/Drum & Disc/Disc Applications. The lid is a screw-top style with hex screws. -These master cylinders are sold individually, or in a kit that includes a proportioning valve. You'll find the parts you need to get the most out of your factory Brakes, These are avalable in Black or Polished Versions