This filter/regulator assembly is commonly used when adapting return style fuel systems for use with returnless applications. Popular for simplifying the fuel system for LS swaps or standalone EFI systems such as Holley, FiTech, or FAST designed to operate on 58psi of static supply pressure. When mounted near the fuel tank this filter allows you to run a single fuel feed line to the engine and just a short return loop back to the tank. Includes: Fuel Filter/Fuel Pressure Regulator assembly Performance -6AN Conversion Fitting for Oulet Performance -6AN Conversion Fitting for Inlet Performance -6AN Conversion Fitting for Return This is the correct filter/regulator required for LS Swaps using returnless style fuel rails and also popular when doing popular the TBSS/NNBS Gen IV intake manifold swap. Using this filter/regulator between the returnless style fuel rails and your return style fuel lines allows for a plug and play style conversion for retrofitting TBSS/NNBS intake manifolds onto 99-04 return style NBS (Silverado/Sierra) truck and other applications. This fuel filter features an internal bypass that regulates fuel output pressure to 58psi. The filter features a 3/8 male inlet, 5/16 male return outlet, and a 3/8 female supply outlet. This fitting combination makes for simple plumbing of fuel systems for LS Swaps and aftermarket EFI conversions. Note: The Filter/Regulator is capable of flowing a maximum of 255LPH. Beyond that amount, there is the potential for fuel pressure creep as the flow rate can overwhelm the internal regulator.