Swartchild Black Shield Mainspring for Rockford 0s #1077 - Steel

Swartchild & Co Black Shield Mainspring No.4389½ for Rockford 0s 1st and 2nd model movements, Factory No. 1077, steel, new in envelope. Swartchild Mainspring Catalog (which I sell) lists this as a Dennison 8 x 9. See image 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.