Check the listing for details. Adjustable Proportioning Valve with 10 lb Residual Valve Kit Drum Drum Valves. Condition: New. Listed at 35.99 USD. This is a brand new Drum/Drum residual brake pressure valve set (TWO 10lb Red Drum valves) and a new adjustable proportioning valve. These valves are used with a disc brake application where the master cylinder is located under the floor. When the master cylinder is under the floor, it is usually lower than the calipers. Gravity and vibration can cause brake fluid to leak back to the master cylinder away from the calipers, causing a loss of brake pressure. These valves will act as a one way check valve that prevents this type of bleed-back. Without it, there is a good chance that the brakes will drag or give out completely! These valves are an inexpensive and necessary addition to your brake system. This is for TWO red valves (for drum/drum applications) and a Black Adjustable Proportioning Valve. This adjustable proportioning valve is designed to be installed in the brake line, in order to adjust pressure in the brake system to keep the brakes from locking or engaging too soon. Specs:3/8-24 fitting sizePressure adjustments range 100-1000 PSI and provide for a maximum decrease of 57% in line pressure“IN” (Stamped on valve) – Rigid brake line from the distribution block to this port. On early cars: the master cylinder rear port to this port“OUT” (Stamped on valve) – Rigid brake line to the rear flex hose“DECREASE” – Reduces the brake line pressure to the rear brakes“INCREASE” – Increases the pressure to the rear brakesMaximum pressure regulation: 300 psiInlet port of valve: 1/8 – 27 NPTStandard adapters: 3/8” – 24 for 3/16” lineMounting hole diameter: .250” (two)Large knurled knob for adjusting to your specificationsMounting holes pre-drilled for vertical or horizontal installationBrass adapters for your brake lines Please Note: Professional Installation is Highly Recommended (No Instruction Included)