Elgin DuraPower Factory Mainspring for 11/0s grades 644-645 - Alloy

Elgin Factory DuraPower Mainspring factory No. 6621-E for 11/0s grade 644 & 645 movements, alloy, new in sealed envelope. See image for specifications. I have several of these so the actual one you receive may differ slightly from the image. I specialize is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item