... preservation 4.ISO,CCC,CE approved NameDetailsOuter water tank:color coated steel or stainless steel with ... rate:93%thermal radiation rate:6%Features for solar collector: 1, freeze-proofing, anti-scale, water purifier (optional ... -proof.3, forceful consolidation of water tank and vacuum tubes, no water leakage.4, streamlined integration of bracket ... or architecture perfectly. incline solar water heater