Endurence Mainspring #123½A for Gruen 405, 420, 421, 425, 426, 420SS, 421SS, 425SS - Alloy

Endurence Mainspring #123½A for Gruen caliber 405, 420, 421, 425, 426, 420SS, 421SS, 425SS 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.