A nice picture of insulators in Rockford, Ill. 1917along the Rock River downtown by the morgan street bridge. ..1917 era. Look at the large power insulators that supplied power to the booming factories then. Can anyone determine what they are, if so let me know....thanks Paul for your help ID of these pieces... Paul Greave mentioned the following quote: I'd give pretty good odds that the ones on the right are M-2430's. The ones on the left look like something similar to M-2231, M-2250B or M-2254. Of course, it is hard to identify the manufacturer! Locke or Thomas are good possibilities. Other possibilities include New Lexington, Ohio Brass or Pittsburg. Not much more I can tell you.