Optical sensors on the back of the watch detect blood flow under the skin and measure heart rate. In addition, other sensors measure acceleration (pedometer), magnetic direction (compass), pressure (altimeter/barometer) and temperature (thermometer). These five high-precision sensor functions measure activity in real time. Captures data of current position from GPS satellite, measures distance traveled, speed, pace and other data. In addition to GPS, the watch acquires data from GLONASS and Michibiki satellite systems. The time mode (including step count measurement and notification functions) can be powered by solar charging alone. The watch also offers a USB interface for even faster charging. After about 2.5 hours of charging, the training functions can be used continuously for up to 14 hours. Uses heart rate and running speed to calculate the maximum consumable oxygen intake per kilogram of body weight in one minute (ml/kg/min). This can be used as a measure of cardiorespiratory fitness when the user is trying to improve endurance for running or other sports. Has a water resistance of 20 bar also with a built-in optical sensor that measures heart rate at the wrist The curved surface of the resin back reduces interference with the back of the hand. Large buttons and two colored buttons with non-slip design improve usability.