Gruen Factory Mainspring for Gruen caliber 460, 470 - Steel

Gruen Factory mainspring for caliber 460, 470 movements, and quite likely others, steel, new in envelope. Yes, these are clearly marked unbreakable but they are NOT alloy mainsprings, just steel ones Gruen insisted would not break. 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 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.