Solar Water Heater, Solar Tubes, Electric Heater, Split Solar Thermal Collector KE58A Vacuum tube: 58x1800mm Inner tank: Stainless Steel 304 2B food grade Outer tank: Aluminum Galvanized sheet Folded from mould with powder painting Outer tank dia.460mm Frame: Aluminum with anti-oxidation treatment Insulation: 50~60mm polyurethane total forming with pressure and best density 40kgs/m3 Available sizes: 18, 20, 22, 24, 28, 30, 36 tubes with capacity 135L up to 325L