Alloy Mainspring for AS 1031, 1039, 1167, Felsa 4010 to 4030

Unmarked Maker Swiss Mainspring for AS caliber 1031, 1039, 1167 and Felsa caliber 4010 to 4030 movements, plus similar ébauche watches, GR Ref. 3700, white alloy, new in tiny 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.