... .4. OEM allowed5. certificate :CE 6. application fields: heating element, drying equipment, cooking device, medical equipment,fry&baking equipment, sterilizing device7. technical datasilicon dioxide ... .95%transmittance of visible light>90%,OH content less than 50ppm,20ppm,15ppm,10ppm,5ppm U-shaped Semi-clear Quartz Tubes with CE