Waltham Factory Mainspring for 18s Model 1870 KW No. 2207 - Steel

Waltham Factory Mainspring Factory No. 2207 for 18s Waltham Model 1870 Key Wind, steel, new in envelope.  See image for further details. I likely don't have several of thee so grab them while you can. I inspect all these old steel mainsprings carefully before I list them and I guarantee them unconditionally. Images do a pretty good job of representing the item.