Progress Mainspring for 0s Elgin Factory No. 825 - Steel

Progress Mainspring for Elgin 0s movements, Factory No. 825, DB&H, steel, new in envelope. See images for further details.  I likely have several of these so the one you get may differ very slightly from the images. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do an adequate job of representing the item.