NuREZISTA Mainspring #647 for 14/0s Hamilton No. 5021 - Steel

NuREZISTA  Mainspring #647 for 14/0s Hamilton Movements, Factory No. 5021, steel, new in envelope. See images for precise mainspring specifications. I specialize in hard to find watch parts and all watch parts are guaranteed. Images do a pretty good job of representing the item.