Newall Security Mainspring #707 for Howard 12s Factory No. 552 - Steel

Newall Security Mainspring #707 for Howard 12s Model 1908 17-21j movements, Factory No. 552, Hole end, steel, new in likely distressed envelope. See image for further details. I likely have several of these so the one you get 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.