Gruen Factory Mainspring for Gruen caliber 405, 410, 420, 425 - steel

Gruen Factory mainspring for calibers 405, 410, 420 & 425 movements, and quite likely others, steel, new in open envelope. I likely have several of the so the one you get may differ slightly from the images but they are all the same mainspring. I specialize in hard to find watch parts so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.