The Features of?Hot Water Storage Tank????????? 1.Innner Material of hot water storage tank:304-BA, food grade stainless steel with thickness 1.5mm to 2.0mm.??????? 2.0.5mm color steel as outer shell material is featured with better anticorrosion resistance,bright color and beautiful appearance????????? 3.Copper coil thant installed in the water tank for energy exchange.??????? 4.Capacity available for hot water storage tank Different models for your choice, available from 80liter to 600 liter.