The Disc/Disc aluminum made brake master cylinder is plated by chrome. The top is flat with bolts installed. The bore diameter is 1-1/8″ equal to 28.58mm. There are two ports with the size of 9/16″ & 1/2″. The fitment is 1977-1982 Chevrolet Corvette, 1964-1966 Chevrolet Chevelle, and 1964-1966 Chevrolet Malibu.