Comsco Mainspring #2161 for Illinois 3/0s Factory No. 47359 - Steel

Comsco Mainspring #2161 for Illinois 3/0s movements, Factory No. 47359, steel, new in envelope. See image 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 barely adequate job of representing the item.