... borosilicate 3.3, thickness: 2.0mm,insulation: rock wool, and import PU,hailstone resistance: 25mmbracket: aluminum alloy, thickness: 3.0mmfeature ... full system completely autumatic, you can uae hot water anytime, high efficient,and no-pollution.3. installation: instal full system is ... pipe for transfer hot, more high efficient, and water more clear,because no water in tube so can work in bad weather ...