Swartchild Black Shield Clock Mainspring 9.0 x .28 mm x 45½” - Steel

Swartchild & Co Black Shield Clock Mainspring, HOLE End, 9.0 x 0.28 x 45½”, MS124 (80-617), steel, new in envelope. I may have several of these so the exact packaging may be different but they are the same mainspring. 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