Elgin DuraPower Factory Mainspring for 13/0s grade 730 & similar - Alloy

Elgin Factory DuraPower Mainspring for 13/0s grade 730 which is a 21j B.W. Raymond movement, alloy, new in envelope. There are several strengths for these 13/0s movements and those than I can supply are shown in the drop down list. Often not an easy mainspring to find. I may 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 guaranteed. Images do an adequate job of representing the item