Comsco Mainspring #10751 for 10s Elgin Factory No. 823 - Steel

Comsco mainspring #140 for Elgin 10s 1st model KW movements, Factory No. 823, SB&H end, steel, new in envelope. See images for further information. I see this model of mainspring about once or twice every 5 years so if you have an super-duper early 10s key wind that uses the Single brace and hole type end this is the mainspring you need. 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.