Newall Security Mainspring #138 for Gruen caliber 641 - Steel

Newall Security steel mainspring No. 163 for Gruen caliber 641 movements and perhaps other watches as well, 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.