Elgin Factory Mainspring for 4/0s Grade 790 - Steel

Elgin Factory for 4/0s Grade 790 movements, steel, new in envelope. The Grade 790 is a German PUW 570 17j based movement. I likely have several of these so the one you receive may differ slightly from the images. 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