Newall Security Mainspring #787 for Illinois 18/0s No. 47383 - Steel

Newall Security Mainspring #787 for Illinois 18/0s, Factory No. 47383, Steel. See images for further details. Notice that these are almost always incorrect marked 47783 instead of 47383. 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.