Edelbrock fuel pressure regulators #174021 are machined from aircraft quality aluminum for those who demand the best. These EFI fuel pressure regulators have an internal diaphragm made of fluorosilicone to ensure high temperature protection resulting in an extended life. They are compatible with all grades of gasoline, ethanol, methanol and E85 fuels. These regulators will hold fuel system pressure for at least 20 minutes after pump shutdown. Mounting bracket and hardware are included. Each regulator features a vacuum/boost compensating port for a supercharger, turbo or intake manifold vacuum connection.