Swartchild Black Shield Alarm Clock Mainspring 4.00 x .20 mm x 21½ Junghans 59 / 60

Swartchild & Co Clock Mainspring, OPEN LOOP End, Dennison 5/32 x .008 x 21½, from the 1950's, steel, made in France. This is the ALARM side mainspring for H.A.U. 60, Junghans 59 / 60 & Blessing 38 caliber movements. See images for precise mainspring specifications. The stain on the envelope is leftover tape sticky-goo. I specialize is hard to find watch & clock parts and all parts are unconditionally guaranteed. Images do a pretty good job of representing the item