Marathon Mainspring #408 for Hamilton 6/0s No. 2321 / 2521 - Steel

Marathon steel mainspring #403 for Hamilton 6/0s movements, Factory No. 2321 / 2521, new in envelope. See images for precise mainspring specifications. 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.