Swartchild Black Shield Mainspring for Rockford 0s No. 1077 - Steel

Swartchild & Co Black Shield Mainspring No.4389½ for Rockford 0s 1st and 2nd model movements, Factory No. 1077, 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 specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.