... .Anti-freezen & pressurized 3.10 years warranty Solar water heater frame Material of Model:1.the heater pipe is made of ... SS-AL-Nx/Cu selective absorption coating;life:15 year3.frame:aluminum alloy,thickness:2.0mm4.water tank:color steel plate ... term performance4) Light-weight - easy to transport5) Attractive design, standard frame suitable for pitched roof or flat roof6) Reliability and long ...