... EN12975, Solar key mark,SRCC,CE,ISO. 2. 0.68~0.73 premium conversion Vacuum tube solar collectors -- Keymark/EN ... -12975,SRCC,ISO,CE,CCC Feature: Working principle1) ... aluminum alloyManifold header pipeTU2 copperInsulation layerCompressed rock wool.VACUUM TUBESTube structureAll-glass double deck co-axial structureGlass ...