Chrome Aluminum GM Master With Smooth Top. This master cylinder features a beautiful chrome finish with smooth top. Master cylinder has a 1" bore and includes ports on both sides to work with all applications (one 9/16" & one 1/2" per side). This is a new master cylinder not a rebuilt or re-manufactured master cylinder. 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.