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