NuVigor Mainspring #240 for Hamilton 0s Factory No. 1535 - Steel

NuVigor Mainspring #240 for Hamilton 0s Movements, Factory No. 1535, steel, new in envelope. Distributed by Burton M. Reid and Sons. See image for specifications and further details. Not a particularly common mainspring. 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.