CR Mainspring #371 for Hamilton 14/0s No. 4128 - Steel

Charles Robert Mainspring #371 for Hamilton 14/0s movements, Factory No. 4128, steel, new in envelope. See images for (very few) further details. 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 unconditionally guaranteed. Images do a pretty good job of representing the item.