Swartchild Black Shield Mainspring #4339 for Waltham 1s & 0s No. 2216 - Steel

Swartchild Black Shield Mainspring No.4339 for Waltham 1s & 0s movements, Factory No. 2216, steel, new in envelope. See images for further details. I likely have several of these so the one you get may vary 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.