Samsonspring Mainspring No. 12A for Gruen caliber 857 - Steel

Samsonspring No. 12A steel mainspring for Gruen caliber 857 movements plus perhaps others, new in envelope. See images for precise mainspring specifications. These are for very old Gruen movements, 1920's and before. 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.