... 10years , 3,beaufiful design Vacuum Tube Solar Collector: 1,Aluminum alloy shell2,Heat pipe vacuum tube3,Nylon vacuum tube holder4,Silicon aluminum&polyurethane ... ,Still works as normal as before even onevacuum tube destroys4,Hailstone resistance:25mm5,Higher efficient stable performance, ... high pressure7,It can be used for solar water heater or solarair condition. vacuum tube heat pipe pressurized ...