ELECTRA Mainspring for Waltham 0s Model 1891 No. 2220 - Steel

ELECTRA Mainspring for Waltham 0s Model 1891 Movements, Factory No. 2220, steel, new in envelope. I rarely see this label and I have to think they didn't either make or distribute for all that long. 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.