C&E Marshall Mainspring #405 for Hamilton 11½L grade 678, 688 No. 67821 / 716786 - Alloy

C&E Marshall Mainspring #405 for 11½ ligne Movements Grade 678, 688, Factory No. 67821 / 716786, alloy, 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 is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a good job of representing the item.