Swartchild Black Shield Mainspring 4372B for Hamilton 16s No. 534 - Steel

Swartchild Black Shield Mainspring No. 4372B for Hamilton 16s Motor Barrel movements, Factory No. 534, steel, new in envelope. See images for further details. 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.