Samson Mainspring No. 1586 for Gruen caliber 520 - Steel

Samson steel mainspring No. 1586 for Gruen caliber 520 movements and perhaps others, 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 an adequate job of representing the item.