Expansion coefficient 3.3, size range from O.D 6±0.4mm, W.T 0.5±0.1mm to O.D 315±3mm W.T 9±1.4mm, low-iron silicon sand employed in the raw material upgraded the transmittance to 92%. Widely used in solar heater, crafts and arts, lighting and solar power. We are the only authorized CSP tube manufacturer in China.