Proflow's one-way check valves are designed to prevent the back flow of any fuel, coolant, or oils. Their flapper design provides minimal flow restriction, and the high-quality construction of these valves ensures long-lasting performance. Their PTFE flapper requires a low 3 to 4 psi to lift off of the seat and is resistant to alcohol, methanol, and bio-diesel fuels. These check valves are offered in AN inlet/outlets.