USR Mainspring for Rockford 6s No. 544 - Steel

USR Mainspring for 6s Rockford New Model (N.M.), Factory No. 544, steel, new in envelope. See images for further details. 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.