Crescent Resilient Mainspring for 16s Elgin No. 2542 - Steel

Crescent Resilient Mainspring for Elgin 16s movements, Factory No. 2542, new in envelope. See images for further details. Quite certain this is a Waltham made mainspring just packaged differently. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do an adequate job of representing the item.