Illinois Factory Mainspring No. 47330 for 16s movements - Steel

Illinois Factory Mainspring, Factory No. 47330 for 16s movements, steel, new in likely very 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 is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a marginally adequate job of representing the item.