Triple Sensor Version 3 is the advanced CASIO original technology that makes it possible to pack sensors 95% smaller than those of previous models into a totally new type of compact PRO TREK. Despite their smaller size, the new sensors in this model provide improved reading accuracy and energy efficiency. This new Triple Sensor Version 3 model delivers altitude, barometric pressure, and direction readings that are more accurate than previous models. A Barometric Pressure Tendency Alarm alerts the wearer to sudden changes in pressure readings, which can indicate upcoming weather events.