... 2.Anti-freezen & pressurized 3.10 years warranty Vacuum tube solar collecotr a. Module design, arbitrary combination, harmonize with ... -24-5818SC-H-30-5818Length of Tube1800mmOuter Diameter of Tubeφ58mmTube Quantity1518202430Manifoldcasing material,Aluminum Alloy,Thickness,1.8mm,Insulating ... boron and silicon content 3.3,Structure,Gradual change SS-AL-Nx/Cu selective absorption coating,Vacuum Degree,P ...