Nivaflex Unbreakable Mainspring for Gruen 275 - 280, 540, 541 - Alloy

Nivaflex Unbreakable mainspring N3186 for Gruen caliber 275 thru 280, 540 & 541 plus perhaps other similar ébauche movements as well, alloy, new in envelope. See images for precise mainspring specifications. 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.