... ISO9001 2,Guarantee:10years , 3,beaufiful design Vacuum Tube Solar Collector: 1,Aluminum alloy shell2,Heat pipe vacuum ... tube3,Nylon vacuum tube holder4,Silicon aluminum&polyurethane foam insulation5,Galvanized steel support ... houses3,Still works as normal as before even onevacuum tube destroys4,Hailstone resistance:25mm5,Higher efficient stable performance, ...