AN6 / AN8 / AN10 One-Way Fuel Check Valve. ✔ Available in AN6, AN8 and AN10 sizes. Available Sizes AN6 / AN8 / AN10. High-Quality Aluminium Alloy • Suitable for Petrol & Diesel Fuel Systems. ✔ Suitable for petrol, diesel, biofuel, vegetable oil and paraffin applications.