Weighing in at only five pounds, the MCPV-1 aluminum master cylinder has all the features of a modern braking system in one master cylinder. It has a double-adjustable proportioning valve, removable metering valve (for 4-wheel disc brake cars), stop light switch port, larger capacity (1-quart) and a smaller size than a conventional iron master cylinder. It's approximately the same size as an iron Corvette master cylinder, only much lighter. The MCPV-1 has two circuits: A front circuit with a metering valve for disc front/drum rear brakes, which is removable for 4-wheel disc brakes and a rear circuit that has the double-adjustable proportioning valve and a maximum rear pressure adjustment. The proportioning valve controls the brake pressure between front and rear brakes, while the rear pressure adjustment controls what the maximum pressure is to the rear brakes. They're available in two different bore sizes for most brake applications and come with a polished finish.