Nivaflex Mainspring for 21/0s Hamilton No. 2921 / 718531 - Alloy

Nivaflex Mainspring for Hamilton 21/0s Movements, Factory No. 2921 / 718531, alloy, new in envelope. See images for precise mainspring specifications. 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.