HR Nivaflex Mainspring G621 for FF60, Kurth 257, Benrus BI & BM - Alloy

HR Nivaflex mainspring No G621 for Benrus caliber BI & BM, FF caliber 60, Peseux caliber 220 and Kurth caliber 257 plus perhaps other movements as well, alloy, new in envelope. See images for further details and 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.