Hamilton Factory Mainspring No. 718601 for 22/0s - Steel

Hamilton Factory Mainspring No. 718601 for 22/0s 17j movements and perhaps others, steel, new in envelope. See images for precise characteristics. This is basically equvalent to an older number 6221. 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.