Glass Vacuum tube Name: Glass vacuum tube Origin: China Features: 1)material: Borosilicate 3.3 glass 2)tube diameter: 37mm. 47mm. 58mm and 70mm. 3)Tuhe length: From 1200mm to 2100mm. 4)Glass thickness: 1.5mm 5)Absorptance: >93% Emission: <8% 6)Vacuum degree: Less than 5*10-3pa 7)Hailstone resistance: Up to 25mm in diameter 8)Maximum strength: 0.8 Mpa 9)Stagnation temperature: >200degree 10)Heat ability: 7kg to 10kg per tube 11)Widely used for solar water heater and solar projects. 12)Life time: 15 years