Marco Mainspring #810 for 16s South Bend No. 17528 - Steel

Marco Mainspring #810 for 16s South Bend movements, Factory No. 17528 (the old number was 7525 if you have a really old catalog), steel, 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 in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.