unpressurized solar water heater 1.CE mark 2.Adjustable frame,easy and safe to use and protects freezing 3.Good quality unpressurized solar water heater1.Outer water tank:non-corrodible colored steel,0.4mm thickness 2.Inner water tank:SUS304-2B stainless steel(food class),0.4mm thickness 3.Vacuum tube:high quality borosilicate glass,AL-N-AL coating,1.5mm thickness4.Heat Preservation:Polyurethane ...