glass tube ,which is produced through the advanced  productive technique of continuous smelting method, it has the characteristics of high purity, strong transmission , good thermally stable function, clear surface, low contents of hydroxide radical , it is the first used materials of producing halogen lamp , mercury vapor lamp , metal halogen lamp, the contests of hydroxide radical can be controlled within 20PPM\10PPM\5PPM\2PPM according to the demands of customers.