Comsco Mainspring #1100 for Hamilton 18s Factory No. 15 - Steel

Comsco Mainspring #1100 for Hamilton 18s movements, Factory No. 15, steel, new in envelope. See images for precise mainspring specifications. 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.