Marco Mainspring #790 for NY Standard 10/0s New Model No. 1324 - Steel

Marco Mainspring No. 790 for NY Standard 10/0s "Crown" movements, Factory No. 1324, steel, new in envelope. See images for further details. Not an easy mainspring to find. 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.