Nivaflex Unbreakable Mainspring for Angelus 55 & Aurore 121 +many more - Alloy

Nivaflex Unbreakable mainspring No 4182 for Angelus 55, Aurore 121, Benrus AB, AG, AL, Bulova 6AH, 6AU, 6AZ, 6BL, 6BS, 6BU, Tavannes 420 to 426 and bunches of other calibers plus perhaps other similar ébauche movements as well, alloy, new in a very messy envelope. See images for further data and 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.