Swartchild Black Shield Mainspring 440741 for Hamilton 16s No. 534B - Steel

Swartchild Black Shield Mainspring No. 440741 for Hamilton 16s Motor Barrel RR 992B movements, Factory No. 534B, steel, new in envelope. See images for further details. Swartchild mainsprings are often just repackages Hamilton Factory mainsprings, as this one is.  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.