CR Mainspring #516 for N.Y. Standard 10/0s No. 1324 - Steel

Charles Robert Mainspring #516 for N. Y. Standard 10/0s, Factory No 1324, steel, new in a very frail envelope. See image for further details. These were made for the 10/0s "Crown" movements and can be tricky to find. 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.