South Bend 18s Mainspring No. 9525 Made by Elgin - Steel

South Bend 18s Mainspring Factory No. 9525 made by Elgin, steel, new in envelope. This is is a beautiful mainspring made for very early South Bend 18s movements and is a very difficult number to find, see images for precise mainspring specifications. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do an adequate but perhaps incomplete job of representing the item.