Non-pressurized Solar water haeter with 5L assistank tankMaterial and Feature:Outer tank material :stainless steel 0.31-0.55mm thickness antirustInner tank Material: SUS304-2B stainless steel 0.31-0.5mm thickness food grade innocuityInsulation layer between outer tank and inner tank material:High density polyurethane foaming 50-65mm thicknessVacuum tube material :borosilicate glass/Three target vacuum tubeVacuum tube QTY:24pcsWater tank capacity:200LAvailable vacuum tube QTY:15/16/18/20/22/24/26/28/30/36pcsAvailable tank capacity: 130/140/150/170/190/200/220/240/250/300L