... certification of CCC,CE&ISO9001 4Manufacture solar vacuum tube 1,vacuum tube length:47/1500mm,58/1800.2,vacuum tubes:15pcs,18pcs,20pcs,24pcs,30pcs3 ... tube58-1800mm co-axial structure high borosilicate 3.3 glass vacuum tube with tube wall thickness of 1.6mm.Inner tank materialSUS304-2B ... tank for 5 years, tube and frame for 15 years Working principle:1,The high quality vacuum tubes ansorb the solar ...