Swartchild Black Shield Mainspring for Illinois 12s/13s No. 47337 - Steel

Swartchild Black Shield Mainspring #440902 for Illinois 12s/13s movements, Factory No. 47337, 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 is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.