Hamilton Factory Mainspring for 18/0s Hamilton No. 718501 - Steel

Hamilton Factory Mainspring for 18/0s Hamilton 17j Movements, Factory No. 718501, steel, new in possibly frail envelope. See image for precise characteristics. The old number for this mainspring was 2721, which I also sell, these just likely have a significantly newer manufacturing date. 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.