These Rhodes Race Cars 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 Rhodes Race Cars one-way check valves ensures long-lasting performance. Their Teflon® flapper is resistant to alcohol, methanol, Ethanol, and bio-diesel fuels. These check valves are offered in a choice of sizes to suit your needs.