NuTemper Mainspring #660 for Howard 12s Model 1908 Factory No. 553 - Steel

NuTemper Mainspring #660 for Howard 12s movements, Factory No. 553, T-end, steel, new in envelope. See image for precise mainspring specifications. 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.