... treatments:Mill finish,powder coated,anodized,electrophoresis,wooden grain,sandblasting,high oxidation film (24-30um).3.Advantages: 1) corrosion ... strong; 4) elastic ratio, rigid, metal fatigue value are high; 5) transportation, installation is convenient, even scratching the surface ... ; 7 )service life in 30-50 years. 4.Quality Standard: GB5237-2008 Aluminium extrusion solar panel frame structure