The GMT-Master II was originally created in response to demand from professional aviators. Equipped with a device for rapidly moving the normal hour hand in one-hour jumps, it is possible to momentarily display the time in a different zone to the two that have already been set. Locating the hour of the new zone on the rotatable bezel in line with the triangular tipped hand is then all that is required. By resetting the bezel so the triangular marker is aligned with the 12 O\’clock position of the dial you then return to the original time zone.