HR Mainspring No. 490 for Bulova caliber 4AR - Steel

HR Mainspring No. 490 for Bulova caliber 4AR movements plus perhaps other similar ébauche watches, steel, new in envelope. 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 marginally adequate job of representing the item.