In the years following the Apollo 11 mission, the world was in awe.  We had landed a man on the moon.  

And while it was Omega's robust calibre .321 that kept Armstrong and his compatriots on time during their epic mission, the Swiss manufacture kept their nose to the grindstone, producing the Mark series Speedmasters.  These Mark series Speedmasters built on the proven success of the previous, manually-wound chronographs by adding an automatic winding function, as well as a series of additional complications.  

The Omega Speedmaster Mark IV, the third of Omega's Mark Series, featured the robust calibre 1040 with date, center 60-minute chronograph, 12-hour counter at 6 o'clock and a continuous small seconds/24-hour day/night indicator at 9 housed in a barrel-shaped stainless steel case, complete with polished bezel, sun-brushed case middle and polished bevels.