NuRezista Mainspring No. 517 for Elgin 12s Factory No. 1720 - Steel

NuRezista Mainspring #517 for Elgin 12s, Factory No. 1720, steel, new in envelope. See images for further details and precise mainspring specifications. 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.