USR Mainspring for Longines 12s, caliber 18.79, 18.80, 18.89, 18.90 - Steel

USR steel mainspring for 12s (18 ligne) Longines calibers 18.79, 18.80, 18.89, 18.90 pocket watch movements, and perhaps others (including the ABC variants of these calibers), new in envelope. I likely have several of these so the one you get may differ slightly from the images.  I specialize in hard to find watch parts so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.