USR Mainspring for Hamilton 12s No. 1228 - Steel

USR steel mainspring for Hamilton 12s movements, Factory No. 1228 (and likely 3028 as well), 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 is 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.