Marco Mainspring #1001 for 18s Seth Thomas Factory No. 536 - Steel

Marco (C&E Marshall) Mainspring #1001 for 18s Seth Thomas movements, Factory No. 536, steel, new in envelope. See images for precise mainspring specifications and 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.