Elgin DuraPower Factory Mainspring for 21/0s No. 6005 - Alloy

Elgin Factory DuraPower Mainspring for 21/0s movements, Factory No. 6005, alloy, new in envelope. Available in several strengths which you should be able to select from in the drop-down list. The default is the -.0030 which should be suitable for most routine applications. 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.