Illinois Factory Mainspring No. 47337 for 12s & 13s Models - Steel

Illinois Factory Mainspring No. 47337 for 12s & 13s "Extra-Thin" Model movements, steel, new in likely frail envelope. One of the beautiful thing about factory mainsprings is that they pretty much always fit. See images for further details. 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.