HR Mainspring A308 for 16s Hampden Railway Movements No. 4697 - Steel

HR Mainspring A308 for Hampden 16s Railway Movements, Specifically the New Railway and the Special Railway and perhaps others, Factory No. 4697, steel, new in envelope. See image for precise characteristics. 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.