... 6 usd Export to Israel ,turkey ,Thailand,et both sides open solar tube1. product description :This is not usual solar tube ... heat oil ,water ,air,and other fluid .no coating both ends open tube There is no coating on the inner tube . It ... able to resist the heat loss. 2.SpecificationSpecifications(both sides open solar vacuum tube)StructureAll-glass double-tube structureGlass materialBorosilicate glass ...