... /1000/1200 Φ58×850/1000/1200 Tube (pcs) 12 / 15 / / 20 / 25 / 30 Vacuum Tube Borosilicate glass, red copper heat pipe, aluminum fin ... summer and 42% in winter more than that of normal glass vacuum tube.4) Modularized collector, arbitrary combination with architectural structure, ... international responsibility for integrated system and 15 years for glass vacuum tubes due to original quality problems