Swartchild Black Shield Mainspring for Illinois 0s No. 47359 - Steel

Swartchild & Co Black Shield Mainspring No.4383 for Illinois 0s & 3/0s movements, newer Factory No. #47359 (older No. was 981), T end, steel, new in envelope. Swartchild Mainspring Catalog (which I sell) lists this as a Dennison 8 x 8. I have several of these so the one you get may vary 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.