These Aeromotive high-flow one-way check valves are designed to prevent back-flow with minimal pressure drop. AN O-ring male inlet/female outlet connections allow easy installation into a fuel pump outlet port without adding additional lines, hose ends, or fittings. They're ideal for use when preventing drainback after the fuel pump is turned off, or when dual pumps are employed and both pumps will not always be running together. They're CNC-machined of 6061-T651 billet aluminum alloy, come available in two sizes, and feature a Type II bright dip anodized finish.