NuTemper Mainspring #652 for 21/0s Hamilton No. 2921 - Steel

NuTemper  Mainspring #652 for 21/0s Hamilton Grade 995 Movements, Factory No. 2921, steel, 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 in hard to find watch parts and all watch parts are guaranteed. Images do a pretty good job of representing the item.