Comsco Mainspring #10750 for Elgin 12s No. 4640 - Steel

Comsco Mainspring #10750 for Elgin 12s Thin Model Movements, Factory No. 4640, steel, new in envelope. See images for precise mainspring specifications and further details. This can be an difficult mainspring to find as it's specific to the thin model 12s movements. 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.