Summit Racing SUM-G3905 Brake Proportioning Valve, Knob Adjustment, 1/8 in. NPT, Single Inlet/Outlet, Aluminum, Natural, Each - Made from aluminum, Summit Racing adjustable brake proportioning valves can be mounted vertically or horizontally. A turn of the knob adjusts the brake proportion on your vehicle to help tailor your brakes to your exact requirements. Multiple versions are available as standalone units or kits with mounting bracket and lines.