1.solar water tank, 2.assistant tank(15L), 3.fill in cold water automaticlly for solar water heater Specification1. Material of inner tank: SUS304/2B2. Material of outer tank: Color armor plate or stainless steel3. Capacity: 5L, 10L, 15L4. Thickness of insllation: 25-30MM5. Fill in the cold water by automatic. assistant Tank for solar water heater(CE, CCC, ISO9001:2000)