Brake Master Cylinders with Reservoir, Matco The MC5 is a vertically mounted master cylinder (within 15° of vertical) with a built-in reservoir. The MC5 is used individually or in a dual brake application in which it acts as the remote reservoir for the MC4 master cylinder. It measures 8.00" long with a 5/8" bore and 1.5" stroke. Fitting hole is 1/8 NPT. It uses Buna-n O-rings and requires MIL-H-5606 red aircraft hydraulic fluid.