Marco Mainspring 3011 for Gruen 300, 301, 307, 327, 328, 329, 350, etc. - Steel

Marco Mainspring 3011 for Gruen 103, 300, 301, 307, 327, 328, 329, 350, 520, 530, 531 caliber movements plus perhaps others, steel, new in envelope. See images for precise mainspring specifications. I specialize is 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.