Alloy Mainspring for Gruen caliber 861 Automatic

Unmarked Maker Swiss Mainspring for Gruen caliber 861 automatic movement plus perhaps similar ébauche watches, white alloy, new in tiny package. See images for further details.  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 an adequate job of representing the item.