... 3)ALN/AL-SS/CU Coating 4)Long life-span vacuum tube : Certifactes: CE, ISO9001; CCCSpecification:1.Outer Diameter ... Φ47/37mm; Φ58/47mm ; Φ70/58mm2.Length of Tube : 1500mm, 1800mm, 2000mm, 2100mm3.Material: Borosilicate glass 3.3 ... , Thickness of tube:1.6± 0.1mm,2.0± mm;4. ... m2 º9.there is no water in the vacuum tube.10. copper pipe transfer heat quickly11. 15year ...