Marco Mainspring #712 for 16s N.Y. Standard Factory No. 1321 - Steel

Marco Mainspring #712 for 16s N.Y. Standard, Factory No. 1321, steel, new in envelope. Typically found in the Crown marked movements but fit others as well. 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.