Marco Mainspring #750 for NY Standard 6s New Model No. 727 - Steel

Marco Mainspring No. 750 for NY Standard 6s New Model movements, Factory No. 727, Hole end, 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.