Imported SWISS Mainspring No. 15 for 18s Hamilton Pocket Watch - Steel

Imported SWISS Mainspring for 18s Hamilton Pocket Watches, Factory No. 15, steel, new in envelope. See images for precise mainspring specifications. I likely have several of these so the one you get may differ slightly from the images. I'm sure the ship and Swiss flag represent a maker name, but I don't know what it is. I specialize is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a marginally adequate job of representing the item.