Air compressor 90 degree elbow unloader valve. This universal unloader valve assembly fits many commonly imported 2-stage air compressor pumps. This valve is located on the hydraulic unloader assembly on the front of the pump directly opposite the crankshaft. A 1/4" copper or aluminum tube runs from this valve to the head of the compressor or check valve and unloads the head pressure once the compressor shuts off. If the compressor is not unloading, this is the valve that needs to be replaced. If this valve continually leaks when your compressor shuts off, your check valve needs to be replaced. Specifications: 90° Elbow Unloader Valve Fits Most Imported 2-Stage Compressors Unloads Head Pressure 1/4" Compression x 1/8" Straight Pipe Material: Brass