is embossed with a Triangle M, which indicates it was made by the Illinois Electric Porcelain Co. in Macomb, IL. The front is embossed: PARALLEL / KNOB / PAT APPL FOR and the back was stamped with the inventor’s name. The purpose of the knob was to secure a telephone drop wire without the use of a tie-wire. The angle that the loop of insulation covered wire took through the insulator body and the gripping serrations above the central knob held the telephone line securely. Undoubtedly there were simpler and less expensive methods to perform the same
