1,Name:Silicone O-Ring 1,Good qulity&best price 2.Sizes:as ... hardness for your option, including Buna-N (NBR), HNBR, VITON, Silicone, FluoroSilicone, EPDM, Teflon, Natural Rubber, BUTYL, SBR, Neoprene, HYPALON, etc ... DVGW certification and British WRAS (WRC) drinking water standard certification. Silicone O-Ring