Reduce the incoming water pressure from the water source with the pressure regulator. When used properly, the lower pressure helps prevent fittings and emitters from popping off and optimizes drip system performance. This pressure regulator is preset to 40 PSI. It has a flow range from 0.2 to 10 GPM. The arrow printed on the body indicates the direction of water flow when installed. The device has a 3/4 in. FPT inlet and 3/4 in. MPT outlet. Made of ABS.