The Rolex GMT-Master wristwatch was originally designed in collaboration with Pan American Airways and issued by the airline to their crews on long-haul flights. ("GMT" in the name stands for Greenwich Mean Time also known as Coordinated Universal Time).[2] The original GMT Master watch has a 24-hour display fourth hand complication directly linked to and displaying the same time zone as the standard 12-hour hand. This GMT hand enabled the crews to set the watch to GMT or another time zone, and, using the rotatable 24-hour scale bezel, set to the correct offset, a second time zone could be read. GMT or UTC is the time zone that is required for all aviation planning, weather forecasts, schedules and other paperwork. Picture of the model 16710, K-serial (model year 2003) In the early 1980s the Rolex GMT-Master II was released (although production of the original version continued alongside it until the late 1990s). Although the watch looks almost identical it uses a movement that has the additional capability of an independently adjustable quickset hour hand that can be adjusted to local time without stopping the seconds or disturbing the minutes and 24 hour GMT hand. As the watch continues to feature the rotatable bezel it is able to quickly compute any third time zone reference. Although the original Rolex GMT Master was available only in stainless steel, as it was conceived as a functional work watch, Rolex has been making luxury versions in both mixed steel and gold, and all-gold since the 1950s, and there are even exotic variations that incorporate elaborate designs that include precious stones.