Progress Mainspring for 16s Trenton Factory No. 344 - Steel

Progress Mainspring for Trenton 16s movements, Factory No. 344, new in envelope. These are hard to find in the proper strength, however, these come more set that I wish they were, which is not uncommon for Progress springs, so they are priced accordingly.  That said, they'll work just fine as a replacement for a broken mainspring. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do an adequate job of representing the item.