Illinois Factory Mainspring Factory No. 47316 for 16s movements - Steel

Illinois Factory Mainspring Factory No. 47316 for 16s movements, steel, new in possibly frail envelope. See images for further details. One of the beautiful thing about factory mainsprings is that they pretty much always fit. 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.