Swisscraft Mainspring #2720 for Gruen caliber 405, 406, 410, 411, 420, 421, 425, 426 - Steel

Swisscraft Mainspring #2720 for Gruen caliber 405, 406, 410, 411, 420, 421, 425, 426 movements, steel, new in envelope.  See images for precise mainspring specifications. 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.