Hamilton Factory Mainspring for 12s Hamilton 17 Jewel No. 1228 or 3028 - Steel

Hamilton Factory Mainspring for 12s 17 Jewel Movements, No. 1228 or 3028, steel, new in often frail or even sliced envelope. These were available in several different strengths and those that I can supply are shown in the dropdown list. See images for precise characteristics. I likely have several of these in each strength 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 marginally adequate job of representing the item.