... solar keymark 2.Anti-freezen & pressurized 3.10 years warranty Vacuum tube solar collecotr a. Module design, arbitrary combination, harmonize with ... allows us to be highly competitive. Solar collector(Heat pipe series)SC-H seriesModelSC-H-15-5818SC-H-18-5818SC-H ... 150W,Working pressure,4Mpa,welding pressure 4MpaDust Ring GasketSilicon Rubber Vacuum Tubetri-element tube,High boron and silicon content 3.3 ...