... :aluminum alloy,thickness:2.0mm4.water tank:color steel plate thickness:0.5mm outertank,and inner tank stainless steel ... capacity: 150L,200L,250L,300L,400L,500L,600L,700L,800L............solar water collector1) Reliable, efficient, twin-glass evacuated tubes2) ... frame suitable for pitched roof or flat roof6) Reliability and long life7) Significant advantages over flat plate8) Easy plug-in installation9 ...