hhlt (smart) flange type level transmitter can carry on accurate measurement of level and density for all kinds of containers. level flange and insert flange are available. flange has 3 inches or 4 inches. specification has 1501b and 3001b flanges. we may also have flange custom-made. if not illustrate our company will provide 3-inch 1501b flange. flange membrane materials are optional.