BOREL Mainspring SA350 for E. Howard 18s No. 55 - Alloy

BOREL Mainspring SA350 for E. Howard 18s "N" movements, Factory No. 55, alloy, new in envelope. See images for precise mainspring specifications. I likely have several of these so the one you get may differ slightly from the images. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.