Complication guide
GMT and second time zone: how the complication works
A GMT watch shows a second time zone on an extra hand that circles the dial once every twenty-four hours, read against a 24-hour scale.
GMT stands for Greenwich Mean Time, the reference the complication was built to track for airline crews. An additional hand sweeps the dial once every twenty-four hours, and read against a 24-hour scale it tells you the time in a second zone at a glance, day or night.
The useful distinction is how the hands are set. In a true or flyer GMT the local hour hand can be jumped forward or back in one-hour steps on its own, so a traveller resets to local time on landing without stopping the watch or losing the home reference. The simpler office GMT only lets you set the 24-hour hand, which suits a watch worn mostly at home.