BESTFIT Mainspring 313C for Gruen caliber 240, 270, 455, Bulova 7AB, NPX 105, Kasper 500 - Alloy

BESTFIT Mainspring 313C for Gruen 240, 270, 455, Helvetia 105, Bulova 7AB, Benrus B, NPX 105, Kasper 500 caliber movements plus perhaps similar ébauche watches, white alloy. See images for precise mainspring specifications. I likely have several of these so the one you get may differ sightly from the images. 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