Steel Mainspring for 0s & 3/0s Elgin No. 2097

Unmarked Maker but likely Swiss made Steel Mainspring for 0s & 3/0s Elgin, Factory No. 2097, DB&H end, new in envelope. See images for further details. 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.