Hamilton Dynavar 10s Mainspring for 917, 921, 923 & 945 No. 20432 - Alloy

Hamilton Dynavar Factory Mainspring for 10s Movements, more specifically the models 917, 921, 923 and 945, Factory No. 20432, 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 don't come across these as frequently as I once did so grab them while you can. I specialize is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a marginally adequate job of representing the item.