... 1.size: OD 3MM-315MM 2.Light,medium and heavy great quality solar vacuum tube & pyrex glass tubes3.3 size: from 3- ... 315mm, and the tubes of 37, 47, 58, 70 for ... water heater.the high borosilicate glass tube enjoys good heat-proof, anti-rot, mechanical capacity, high working temperature, good technical quality and the favourable price ...