Vacuum Tube Solar water heater: high efficiency, TIG welding, reliable quality, good finish, competitive price ... Features of our vacuum tube solar water heater:CE certified, igh efficiency, reliable quality, inner tank TIG welding ... steel, Al-An zinc steel sheet, or Anit-corrosion Fluorine carbon steel plate;Outer tank Dia.: 420mm, 470mm, 600mm;Insulation material ...