industry solar water heater supply hot water for factory, hotel, school, and so on. solar collector Working principle:Combined many collectors with ... swimming pool, school, army, hotel etc.3.Outstanding quality reasonable price4.Can be installed on flat and slope roof ... 0.4-0.6mm4. Insulation material: Imported Polyurethane foam with high density5. Vacuum tube: Borosilicate glass 3.36. Hail resistance: ...