Longines Factory Mainspring for caliber 10/86N - Steel

Longines Factory Mainspring for caliber 10/86N plus perhaps similar ébauche watches, steel, new in open envelope. Just one, not 1/4 doz like the envelope says. The wonderful thing about factory mainsprings is they always fit! 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.