Sandsteel Mainspring #843 for Longines caliber 21.29 - Steel

Sandsteel steel mainspring #843 for Longines caliber 21.29 (21/29) Pocket Watches plus likely other movements as well. 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.