SC solar water heater Model:BLKL-SC420-1500/47-18 Cat.No: SC solar water heater /chinese/index.htm Advantage: 1) The material of the outer tank is Galvanized Steel. The material of the inner tank is SUS304 2B stainless steel. 2) The life of the vacuum tubes is 15 years. 3) Stable and reliable performance, well resistance. 4) Temperature when exposed to sun without water: 250°C, 2.5 hours to boiling point if using single tube. 5) It resists 25mm hail. 6) Heat preservation: 72 hours. 7) optional accessories: assistant tank, electric heater 8) 5 years warranty. Inner tank:SUS304-2B [0.4mm/0.5mm] Insulation layer:Polyurethane foam [55mm] Outer tank:Galvanized Steel [0.4mm] Bracke:Galvanized Steel [1.5mm] Evacuated tube:Borosilicate Glass 3.3 Tubes Qty.:18 Tank (L):120L Absorbing Area (m2):0.9 Weight (KGS):59 Dimension (L×W×H):1400*1360*1700 Qty. per 20FT/40FT/40HQ: 56/112/136 i2-joyce