BOREL Mainspring SA309 for 16s Hampden No. 5697 - Alloy

BOREL Mainspring SA309 for Hampden 16s Movements, Factory No. 5697, Hole End, alloy, new in envelope. See image for precise characteristics. 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.