Illinois Factory Mainspring No. 47363 for 6/0s O.F. movements - Steel

Illinois Factory Mainspring No. 47363 for 6/0s open face wrist watch 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.