1.Glass vacuum tube solar collector, high temperature,antifreeze,vacuum insulation.2.Food-grade stainless-steel SUS304 2B inner tank,full-automatic welding technology,under the protection of magnesium rod,it can increase of service life. 3.High pressure polyurethane foaming insulation,as the prefect density and the thermal conductivity coefficient is small, so it can provide effective heat preservation 4.The outer tank adopt color steel plate,and it has good double anti-corrosion function. http://www.sidite-energy.com