Nivaflex Mainspring for Gruen 400, 405, 410, 420, 425, 430, 440, 500 - Alloy

Nivaflex mainspring No 123½X for Gruen caliber 311, 330, 335, 400, 405, 410, 420, 425, 430, 440, 500 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.