Hamilton Factory Mainspring for 18s No. 718012 / 15 - Steel

Hamilton Factory Mainspring for 18s Movements, Factory No. 718012 (or the old #15), steel, new in envelope. See images for 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 so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.