... -S-AL vacuum tubes,Extremely strong transparent glass. stainless steel solar water heater systemSpecifications: 1) Outer shell of heat collector tube: aluminum ... , 58mm x 1800mm4) Volume of tank: 150L, 200L, 250L, 300L5) Pressure: 0.6MPa6) Heat retention: 72h7) Hail resistance: 25mm8) Product structure ... for family, school, hotel, factory and swimming pool stainless steel solar water heater system