Sandsteel Mainspring for Seth Thomas 12s No. 2521 - Steel

Sandsteel Mainspring for Seth Thomas 12s Factory No. 2521, steel, new in possibly frail or damaged envelope. See image for precise mainspring specifications. This mainspring has the distinction on being one of the very few that has a number similar to another makers mainspring, specifically one for a Hamilton 6/0s, which this will not fit so don't confuse them. 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.