H. & W. Perrin Co. Mainspring for Hamilton 21/0s Grade 750, 751 No. 717572 - Alloy

H. & W. Perrin Co. LTD Mainspring specifically for Hamilton Grade 750, 751 movements plus perhaps a couple of others, Factory No. 717572, Alloy, new in envelope. See image for precise mainspring specifications. H. & W. Perrin is the largest supplier of horological materials in Canada. 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 suitable job of representing the item.