HR Mainspring SA603 for 12s South Bend No. 55528 - Alloy

HR Mainspring No. SA603 for South Bend 12s, Factory No. 55528, T-end, alloy, new in envelope. See image for precise mainspring specifications. I likely have several of these so the packaging 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.