Would like any information on this spring type strain. The neat little cobalt blue porcelain insulators are rec-embossed FLERONRADIO and about 1-1/8" by 3/4". The entire length is just over 10 inches. The 1" steel spring is quite tightly wound. Any help in finding out what it was used for or age is greatly appreciated. .....Mike Martin wrote in with this info: This is a constant-tension radio antenna strain insulator made for use on longwire antennas, some of which were commonly supported by a convienent tree at one end. Since trees sway in the wind, the spring tended to prevent excessive movement of the wire which could de-tune it and reduce its efficiency, and also helped to prevent the wire from breaking under a sudden pull. Another popular method of hanging an antenna was to support the wire from a cable or rope attached to a pulley and weight on a tree or a pole, but this was harder to install. Probably made sometime in the 1920's or 1930's, though wire antennas were used by ham operators much later than that (and still are today to some extent). M.M. Fleron & Sons was a distributor of radio parts. Thanks Mike for your help.