Proflow fuel pressure regulators are designed to precisely control the fuel pressure from the fuel pump to the carburetor. Too much fuel pressure for a given needle and seat assembly can overload the needle and seat and may cause flooding or drivability problems. Each Proflow fuel pressure regulator is fully adjustable so regulating the fuel pressure to your engines needs is a simple task. All Proflow regulators are pre-set at the factory so there is no guesswork when first installing the regulator. The Proflow PFEFS12803 fuel pressure regulator features 3/8" NPT in/out ports.