Marco Mainspring #490 for 18/0s Hamilton Movements No. 2721 - Steel

Marco Mainspring No.490 for 18/0s Hamilton Bracelet Watch movements, Factory No. 2721, steel, new in envelope. Could also very well fit in other models 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.