Made from a 12 flute, mandrel-formed, aluminum tapered. shaft 6 & 7” round (152 & 178 mm) welded to a 6 5/8” round (168. mm) extruded aluminum pole base which is welded top and bottom. to a cast-aluminum anchor plate. After tapering, forming and welding, the entire shaft assembly is heat–treated to T6 temper. A 4 1/2” by 10” (114 by 254 mm) maintenance opening is complete. with cover and copper ground lug.