Hamilton Dynavar 11½L Mainspring for grade 658 & 661 to 665 #821/ 716780 - Alloy

Hamilton Dynavar Factory Mainspring for 11½ ligne Swiss Made Movements (Grades 658, 661, 662, 664, 665), Factory No. 821 / 716780, alloy, new in envelope. See images for further details. 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.