Newall Security Mainspring #757 for 16s Illinois No. 47316 - Steel

Newall Security Mainspring No. 757 for Illinois 16s 19j & 21j RR Movements, Factory No. 47316 or 573 depending on how old your catalog is, steel, new in envelope. See images 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.