Watches featuring dual time system indicate local time in different world cities. They are very appreciated by travelers.
Watches featuring a GMT complication (which stands for Greenwich Mean Time) can display a second time zone thanks to an additional hand. They are much appreciated by travelers and airline pilots.
Watches featuring a « big date » display an oversized window and have two independent date discs.
Watches featuring a small seconds have a smaller subcounter, usually located at 6h, which indicates seconds.