Every item that is inspired by the military can be used for a practical purpose. Included are wrist watches. The military first used wrist watches in the 19th century to coordinate maneuvers during war. Divers have used specialized watches in the deep ocean, while aviators use them high up in the air.
A watch's ability to operate in the field for longer periods of time is a major advantage, especially over a smartphone. Many watches can be powered by motion alone or with a little energy from a battery. You can count on years of reliable time telling. This is compared to 8 hours on a smartphone.
A complex watch has more features than the simple function of showing the date and time. This functionality is known as a complication. The chronograph allows the watch to be used as a stopwatch, and the moonphase complications, which show the lunar phase, are two of the most popular complications. In terms of functionality Seiko Flightmaster offers the best in market right now.