Marco Mainspring #431 for Hamilton 12s Factory No. 3328 - Steel

Marco Mainspring #431 for Hamilton 12s Model 400 21j, Factory No. 3328, 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 in hard to find watch parts and regardless of how it may look, all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.