Sandsteel Mainspring for 16s South Bend Factory No. 17528 - Steel

Sandsteel Mainspring for 16s South Bend movements, Factory No. 17528, 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 a pretty good job of representing the item.