1/4" MNPTF x 1/4" FNPTF Aluminum Anti-Siphon Valve | EVM A/S 163 EVM A/S 163 Anti-Siphon Valve 1/4 in. Male NPTF x 1/4 in. Female NPTF Aluminum Anti-Siphon Valve 160 Series Designed to prevent the siphoning of marine fuel tanks should a fuel line leak or break occu