Swartchild Black Shield Clock Mainspring 2.4 x .17 mm x 19¾" Ref 24-17 C 50

Swartchild & Co Black Shield Clock Mainspring, Tongue End, for Kienzle 31 / 172, 31 / 173 & Muller 36, likely ALARM side only, GR Ref. 24 - 17 C 50, steel, made in France. See images for precise mainspring specifications. 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