Illinois Factory Mainspring No. 47309 for 16s 60hr Railroad Watches - Steel

Illinois Factory Mainspring, Factory No. 47309 for 16s 60hr Railroad Model (Bunn, etc) motor barrel movements, steel, new frail envelope. 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. See images for further details. 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.