Alloy Mainspring for 16s Illinois No. 47331

Unmarked Maker Swiss made Alloy Mainspring for 16s Illinois, Factory number 47331, new in envelope. See image for further details and precise mainspring specifications. 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.