solar water heater : certification:ISO9001,ISO14001,CCC,CE,Solar Keymark solar water heater:heat pipe tube pressure:pressuriz solar water heater: material:1.volume of storage tank:120L,180L,240L,300L2. ... :0.4mm inner tank,stainless steel SUS304-2B,thickness:1.2-1.5mm,normal working pressure:6bar,test pressure:12bar3.dust ring gasket ...