USR Mainspring for Illinois 16s 60hr No. 47309 - Steel

USR Mainspring for Illinois 16s 60hr Motor Barrel movements, Factory No. 47309 (really old No. 1759), steel, new in envelope. See images for further details. I likely have several of these so the one you get may differ slightly from the images. I specialize is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.