Hamilton Factory Dynavar Mainspring for 12/0s No. 44431 - Alloy

Hamilton Factory Dynavar Mainspring for 12/0s Movements, Grades 752, 753 & 754, Factory No. 44431 / 717220, alloy, new in frail envelope. See image for precise characteristics. 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.