DescriptionBarometer Altimeter: The barometric pressure value on the screen is the barometric pressure at the current location. The height value on the screen is the sea level of the current location. Press the [ALTI/+] button to toggle the use of altimeter and barometer.Relative Altitude: Monitor the ascending or descending altitude from a certain location or the altitude relative of a mountain or an object, etc.Weather forecast: In addition to detecting altitude, the barometer also helps predict the weather for the next 12-24 hours based on on changes in barometric pressure. The effective range is 30-50 km. History altitude record: Press the [HISTORY] button, you can view the altitude and atmospheric pressure records of the history. It will show the most previous record in this mode, then you can press [ALTI/+] or [-] button to view the history records forward or backward. It can save most 256pcs records, the distance of records is five minutes, and you can change the distance from 1 to 60 minutes if you press and hold the [HISTORY] button for 2 seconds. Power Saving: When you dont want to use the device, press and hold the [SET] button for 5 seconds, the device will stop all displays and enter standby mode. And then you press any button, it will resume previous display. Backlight: In any mode, it can give you backlight for 5 seconds when you press any button.Description of the productMaterial: ABSHistorical altitude record: record of 256 piecesThermometer: Celsius/Degree Fahrenheit formatClock: 12-hour or 24-hour formatCalendar, backlightPower-saving design: start automatic altitude measurementPower supply: 1 x CR2032 battery 3V (battery included)