SUS304-2B inner tank solar keymark, ccc, ce, ISO9001, SGS good quality, reasonable price, ... of SUS304 food grade stainless steel, thickness: 0.4mm2. Outer water tank material: color steel thickness: 0.31mm3. Heat preservation: 72hours4. insulating ... -N-AL 300L 26 52 66 compact non-pressurized solar water heater