NuTemper Mainspring #670 for Illinois 16s No. 47309 for 60hr - Steel

NuTemper mainspring #670 for Illinois 16s 60hr movements, Factory No. 47309, 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 is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.