Michel Herbelin CAP CAMARAT GMT Mode D'emploi page 11

3.2. Adjusting the second time zone
- The 24-hour hand will always display the hour in
the second time zone.
- Pull the crown out (5) to Position 2 while turning
it clockwise. Position the GMT hand facing the
second time zone of your choice.
Example :
The time is 10:11 in Paris, and you choose Los
Angeles as the second time zone. The time in Los
Angeles is thus 01:10.
All time zones have the same minute reading as
the local time.