Marco Mainspring #579 for 6/0s Illinois Factory No. 47363 - Steel

Marco (C&E Marshall) Mainspring #579 for 6/0s Illinois Open Face 1st and 3rd models, Factory No. 47363, steel, new in envelope. See image for further details. 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.