1)material: borosilicate 3.3 glass2)tube diameter: 37mm.47mm.58mm and 70mm.3)Tuhe length: from 1200mm to 2100mm.4)Glass thickness: 1.5mm5)Absorptance: >93% Emission: <8%6)Vacuum degree: less than 0.005pa7)Hailstone resistance: up to 25mm in diameter8)Maximum strength: 0.8 Mpa9)Stagnation temperature: >200degree10)Heat ability: 7kg to 10kg per tube11)Widely used for solar water heater and solar projects.12)Life time: 15 years