Illinois Factory Mainspring No. 47331 for 16s movements - Steel

Illinois Factory Mainspring No. 47331 for 16s movements, steel, new in envelope. This one is primarily for the Extra Thin Motor Barrel 16s grades. 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 one in 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.