Marco Mainspring #370 for Hampden 3/0s & 5/0s Factory No. 9696 - Steel

Marco Mainspring No.370 for 3/0s & 5/0s Hampden watches (Molly Stark, Diadem, Model 400, etc), Factory No. 9696, steel, new in frail envelope. Could also fit in other watches as well. See images for further details. I likely have several of these so the one you get may differ slightly from the images. 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.