Swartchild Black Shield Mainspring for Elgin 3/0s No. 2097 - Steel

Swartchild Black Shield Mainspring #19460 for Elgin 3/0s, 7j to 15j, Factory No. 2097, steel, new in envelope. See images for precise mainspring specifications. If you have a keen eye you'll notice it is marked 2907 instead of 2097 - every one I've ever seen is like this. Anyhow, this is the strength for the 3/0s not the 0s so be sure to check which 2097 you need. 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.