Longines Factory Mainspring for caliber 19.4, 19.4S - Alloy

Longines Factory Mainspring caliber 19.4 & 19.4S plus perhaps similar ébauche watches, alloy, new in open envelope. The wonderful thing about factory mainsprings is they always fit! I likely have several of these than may be marked a bit differently 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 an adequate job of representing the item.