Product Description Material Inner tank:Food grade 304 stainless steel Outer tank:Food grade 304 stainless steel or colored steel Jacket for heat exchanger:Stainless steel Insulation:50mm polyurethane Flat collector frame:Aluminum Absorber wings:Copper Absorber coating:Black paint Supports:Galvonized steel with painting Electric heater as back up 1piece airvent valve 1piece T/P valve