Swartchild Black Shield Clock OPEN LOOP Mainspring 3.60 x .23mm x 25" - MS-246

Swartchild & Co Clock Mainspring, OPEN LOOP End, Dennison 9/64 x .009 x 25, P/N MS-246 (80-987) from the 1950's or later, steel, new in envelope. See images for further details. 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