Swartchild Black Shield Mainspring for Elgin 5/0s No. 2890 - Steel

Swartchild Black Shield Mainspring #19348 for Elgin 5/0s, 1st & 2nd models, Factory No. 2890, steel, new in envelope. See images for precise specifications. 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.