Comsco Mainspring #1122 for Hamilton 18/0s Factory No. 2721 - Steel

Comsco Mainspring #1122 for Hamilton 18/0s Movements, Factory No. 2721, steel, new in envelope. Distributed by Burton M. Reid and Sons. See image for precise mainspring specifications and further details. 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.