... quality,reaonable price Solar Vacuum Tube of 3 layers,More effective, Original and High qualityThe structure of inner tube SpecificationsStructure All-Glass Double Tube Co-Axial Structure ... ,1600mm,1700mm,1800mm,1900mm,2000mm,2100mm Absorptive Coating Property Three layers of Magnetron Sputtering Plating.Cu/SS-ALN(H)/SS-ALN(L ...