Solar Vacuum Tube three-target solar vacuum tube with ISO9001-2000 ,CE certificate FEATURES OF THREE TARGET SOLAR TUBES AND PURPLE GOLDEN SOLAR TUBEThree target vacuum tube,the solar tube is made from ... .it is widely used in solar water heater,solar collector,solar projects.Name:vacuum tube(three target vacuum tube)Material:inner tube and outer tube(high borosilicate 3.3glass ...