Rezista Mainspring No. 221 for Gruen & Alpina caliber 157 - steel

Rezista No. 221 steel mainspring for Gruen caliber 157 & Alpina 157 (since they're the same movement) and quite likely others. See images for precise mainspring specifications. I specialize is 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.