Marco Mainspring #583 for Illinois 6/0s Factory No. 47371 - Steel

Marco Mainspring #583 for Illinois 6/0s, 4th to 6th model movements, Factory No. 47371, steel, new in envelope. 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 pretty good job of representing the item.