... 'Warranty 3.Delivery:7-20Days 4.OEM,2500Sets/Month heat pipe solar water heater----------------------------------------------Inner tank:Food grade SUS304/2B stainless steel ... .Tube quantity: 15, 18, 20, 24, 30, 32 and 36pcs.Heat insulating layer: Improved polyurethane integral foaming with 50-65mm thick ...