NuVigor Mainspring #91 for Elgin 12s No. Factory No. 1720 - Steel

NuVigor Mainspring No. 91 for Elgin 12s, Factory No. 1720, steel, new in frail envelope. See image for precise mainspring specificaitons. I likely have several of these so the one you get may differ slightly from the images. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item