3.3 borosilicate glass tube with three coating,high efficient. 3.3 borosilicate glass tube specification:1.Structure:All-glass double-tube co-axial structure2.Glass material:High borosilicate 3.33.Diameter and thickness:47mm,1.6mm/58mm&1.6mm4.Length:1500mm/1800mm/2000mm5.Absorptive coating material:Al-N/AL or ALN/ALN-SS/CU6.Life:15 years glass pipe cheap