Tru-Power Mainspring U357C for Marvin 610, Election 845 - Alloy

Tru-Power Mainspring U357C for Marvin caliber 610 & Election caliber 845 movements, alloy, new in envelope. I have a secondary reference that says it also fits Buren 1420, 1421, 1422 and a couple of Doxa movements.  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 an adequate job of representing the item.