CR Mainspring #306 for Hampden 16s Factory No. 5697 - Steel

Charles Robert Mainspring #306 for Duber Hampden 16s Movements, Factory No. 5697, 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.