Newall Security Mainspring #620 for Hamilton 8/0s movements No. 7221 - Steel

Newall Security Mainspring #620 for Hamilton 8/0s movements, Factory No. 7221, 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 is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.