In 1952, the British de Haviland Comet became the first commercial jet airliner in service. With the dawn of the commercial Jet Age, Pam Am approached Rolex about creating a watch specifically for its world-travelling pilots. Two years later, the world was introduced to the Rolex GMT-Master, a watch that allowed its wearer to track two time zones. The watch simply added an additional hour hand that tracked to the now iconic red-and-blue Pepsi 24-hour bezel: blue for nighttime hours, red for daytime hours. It’s called a GMT watch because pilots would set this additional hour hand to GMT time so they could all communicate off a base time. Of course, now wearers will set the secondary hour hand to their home, using the watches main indication for the time zone they are travelling in. While Rolex was the first, many brands now offer compelling GMT watches great for travellers who want a durable, water-resistant watch that harkens back to the early days of aviation.