Marco Mainspring No. 612 for Howard 16s Factory No. 328 - Steel

Marco Mainspring No. 612 for Howard 16s Model 1906 & 1907 movements, Factory No. 328, hole end, steel, new in envelope. See images for further details. I likely have several of these so the one you get may differ 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.