Robusta Mainspring No. 1226 for M.S.T. caliber 358 - 373 - Steel

Robusta No. 1226 steel mainspring for M.S.T. calibers 358 thru 373 and perhaps others, steel, new in envelope. See images for precise mainspring specifications. I specialize in hard to find watch parts so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.