HR Mainspring A603 for South Bend 12s Factory No. 55528 - Steel

HR Mainspring A603 for South Bend 12s, Factory No. 55528, steel, 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 in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do an adequate job of representing the item.