With GMT watches you can display two or, with separately adjustable GMT hands, three time zones at the same time.
For two different time zones, the local time is normally set using the hour hand and the bezel (in the case of a non-adjustable GMT hand) is set to the corresponding time in the desired time zone.
If you want to display three different time zones, you need a separately adjustable GMT hand. This is then set for the corresponding time zone. For example, if the desired time zone is 2 p.m., the GMT hand will be set to 7 a.m.
To set the third time zone, the bezel is aligned with the GMT hand as described above. Now you just have to remember which time zone is what …