Anti-Siphon 1/2 NPT x 1/2 Barb | EVM A/S L-180-B-1/2 EVM A/S L-180-B-1/2 Anti-Siphon Valve 1/2 in. Male NPTF x 1/2 in. Hose Barb Brass Anti-Siphon Valve 180 Series Designed to prevent the siphoning of marine fuel tanks should a fuel line leak or break occur