The new MDR Motorsport adjustable proportioning valve combines the latest refinements to deliver precise pressure metering and strength from a compact, lightweight, billet aluminium design.  They are used to balance the line pressure in a braking system, these are sometimes needed when converting to larger brakes or miss-matched brakes.  Pressure adjustments range from 100-1000 PSI and provide for a minimum 0% to a maximum 57% decrease of inline pressure.   Adjuster knob with fine thread tuning provides precise pressure adjustment. This adjustment lets you fine tune the front to rear braking balance by proportionally decreasing the rear brake line pressure.