Swartchild Black Shield Mainspring #4340 for Waltham 0s No. 2228 - Steel

Swartchild Black Shield Mainspring No.4340 for Waltham 3/0s movements, Factory No. 2228, HOLE end, 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.