Duber Hampden Factory Mainspring 11/0s No. #11696 - Steel

Duber-Hampden Watch Co. Factory Mainspring for 11/0s movements, Factory No. 11696, steel, new in envelope. See image for precise mainspring specifications. Consider please just how unusual it is to find an original factory mainspring from Hampden, but at the same time please know that I inspect these 80+ year old mainsprings very carefully and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.