Elgin DuraPower Factory Mainspring for 21/0s No. 6246 - Alloy

Elgin Factory DuraPower Mainspring for 21/0s movements (Grade 650 & 651, 655, 656, etc.), Factory No. 6246, alloy, new in envelope. See image for precise mainspring specifications. These came in several different strengths and those that I can supply are shown as options in the drop-down list. 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.