Holley Billet Fuel Pressure Regulators are part of a complete line of fuel system products from Holley. They are precision machined from 6061-T6 billet aluminum for strength and durability. These regulators are adjustable from 4-65 psi and will handle both carbureted and EFI applications. A second pressure spring is included allowing you to increase the fuel pressure range up to 65 psi for EFI systems. They are offered with 6AN to adapt to your new or existing fuel lines. So, if you are currently running a carbureted system but plan to upgrade to EFI in the future, these regulators will have you covered either way.