The Duo 24 Green Edition watch by Germany’s Botta Design is the world’s first dual one-hand watch featuring dual time zones. It shows both the local time and the time at one additional time zone, using just one hand in each case. The main hand is a 12 hour hand referencing the 12 hour markers, and the secondary hand is a 24 hour hand referencing the 24 hour ring.
Two relevant times can thus be checked easily at a glance. It has a very simple yet amazingly logical principle, the main scale on the outside of the watch shows you local time while the inside scale you can set to your time zone of choice. Simple and clever.