BESTFIT Mainspring JA229 for 20/0s & 21/0s Hamilton #2921 / 718531 - Alloy

BESTFIT Mainspring MS-JA229 for Hamilton 20/0s & 21/0s Movements, Factory No. 2921 / 718531, alloy, new in envelope. See image 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.