Swartchild Black Shield ALARM Mainspring for Baduf Purse and Kaiser 6/340 Alarm Clock

Swartchild Black Shield Mainspring for Kaiser 6/340 & Baduf Purse 15 Alarm Clocks from the 1930's and 1940's (and perhaps beyond), ALARM side spring, new in envelope. Could also very well fit in other alarm and travel clocks as well. See images for precise mainspring specifications. I specialize is hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a suitable job of representing the item.