... SUS304-2B stainless steel(food class), 0.5mm thickness 3, vacuum tube:47(58,70)mm×1800(1500,1600,2000,2100 ... heater with SOLAR KEY MARK certificate2.High efficiency, Absorption rate: =93%, thermal radiation rate: =6%3.Competitive price, all the parts are ... utilities/governmentHot water during blackouts!No hot water during blackouts solar water heater/vacuum tube collector with CE(18tubes,150L)