Swartchild Black Shield Clock Mainspring 7.0 x .28 mm x 18” Ref 70-25 T 46

Swartchild & Co Black Shield Clock Mainspring, HOLE End, 7.0 x 0.25 x 10”, GR Ref. 70-25 T 46, steel, new in envelope. I likely have several of these so the exact packaging may be different. 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