1,quartz heating rod: 2 purity 99.99 ... nonbrowning no blackline non-discolouring No black quartz heating rod1, quartz heating rod : 2 purity 99.99% min3 ... no airlineSpecification:Outer Diameter: 2-40mmAdvantage of the quartz tube:1. High temperature resistant, 1100 degree ... heating resistance,low OH), UV-stop quartz tube, red quartz tube, processed quartz tube, quartz rod, quartz plate, gray quartz tube ...