Jewell Mainspring for Waltham 18s Keywind No. 2204 - Steel

Jewell Mainspring for Waltham 18s Model 1879 Keywind movements, Factory No. 2204, steel, new in envelope. See images for further details. Not familiar with the maker but it's a nice mainspring. I specialize is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a suitable job of representing the item.