Comsco Mainspring #1135 for Illinois 16s Factory No. 47313 - Steel

Comsco Mainspring #1135 for Illinois 16s RR movements, 21 & 23j, Factory No. 47313, steel, new in envelope. See images for precise mainspring specifications. 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.