Newall SUPER Security Mainspring #658 for 12s Hampden No. 6696 - Alloy

Newall SUPER Security Mainspring No. 658 for Hampden 12s Movements, Factory No. 6696, T end, alloy, new in envelope. See image for precise mainspring specifications. I likely have several of these so the one you get may differ slightly from the images. 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.