HR Mainspring SA220 for 12/0s Hamilton No. 4128 / 718400 - Alloy

HR Mainspring SA220 for 12/0s Hamilton, Factory No. 4128 / 718400, T end, Alloy, new in envelope. See image for precise characteristics. 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.