Gruen Factory Mainspring for Gruen caliber 311, 330, 355, 400, 500 - Steel

Gruen Factory Mainspring for caliber 311, 330, 355, 400, 500  movements, and perhaps others, steel, new in envelope. These are funny because they came back and added other calibers after packaging. 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.