Alloy Mainspring for Junghans caliber 28

Unmarked Maker Swiss Mainspring for Junghans caliber 28 movements (and variants) plus perhaps similar movements, GR Ref. 4704, 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.