Sandsteel Mainspring for Illinois 16s 60hr RR No. 47310 - Steel

Sandsteel Mainspring for Illinois 16s 60hr Railroad movements, Factory No. 47310, steel, new in envelope. See images for precise mainspring specifications. This is the far less common cousin to the 47309. 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 barley adequate good job of representing the item.