National Unbreakable Mainspring for Elgin 21/0s 5327 / 6004 - Alloy

National Mainspring for 21/0s Elgin, Factory No. 5327 / 6004, alloy, new in envelope. See images for precise 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.