Elgin Factory Mainspring for 10/0, 16/0 and 18/0s No. 1957 - Steel

Elgin Factory Mainspring for 10/0s, 16/0s & 18/0s movements, Factory No. 1957, steel, new in envelope. See images for further specifications. These came in different strengths and those that I can supply are found in the drop-down list. I likely have several of these (in each strength) so the one you get may differ slightly from the images. Elgin mainsprings are typically coated in very old grease and must be cleaned before use. I specialize in hard to find watch parts and all watch parts are guaranteed. Images do a pretty good job of representing the item.