This is a rare Vintage Sicura Chrono that has GMT World Time bezel.  

The black dial is in great condition despite it being 40+ years old.  The outer part of the dial is a gold/champagne dial showing 24hr clock times.  All the hour markers are in the same gold/champagne colour that contrasts so well against the black dial.
The Bezel rotates in both directions to operate the GMT World Time function.

At 7 O'clock there is a sub dial for the seconds hand.  The large orange hand is the chrono stop that is reset using the top crown.

The outside of the black part of the dial has a Tachy dial to use for timings.

All in all a very cool looking multi function Diver watch.