TR universal adjustable fuel pressure regulator Pro Series is made for cars with upgraded fuel systems and requires fine tuning on the flow rate of fuel to the engine. The regulators have been outfitted with a 39mm diaphragm to insure your engine gets the perfect amount of fuel while maintain stable pressure at high horse power level. These fuel pressure regulators are made of high quality billet aluminum with an anodized blue steel finish. Each kit comes with a regulator, the mounting bracket and regulator fittings.