Marco Mainspring #2990 for ETA 1321, Bulova 6AM, 6AU, 6BU, Mido 1938, Tavannes 420 - Steel

Marco Mainspring No. 2990 for ETA 1321, Bulova 6AM, 6AU, 6BU, Font 61, 123, Mido 1938, Benrus AG, Felsa 158, 350, Tavannes 420, 424, Unitas 190, 540 caliber movements, 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.