... 304, 316 Outer tank: 0.6mm stainless steel 304 Or coated galvanized steel2. Insulation: 55mm CFC-free foam3. Copper coil: 12#/1mm Or ... , from package design to tech support......3. Various certificates: ISO, EN12975, EU CE, Solar Keymark, Kang-Ju, KOLAS, SABS, SRCC4. Strong warranty ... company have strict quality control and aftersale service. Solar water tank with copper coil or SS ...