Barometer: The current barometric pressure will be displayed on the screen immediately after power on. Press the ALTI/+ button to switch between barometer and altimeter. Altimeter: The altitude value displayed on the screen after power on is the sea level altitude of the current location. In the altitude display state, press the SET and ALTITUDE/+ keys simultaneously, you can press + or - to change the current altitude value. Relative altimeter: The use of the relative altimeter is to clear the height value measured at this time, and use the position at this time as the 0M height point, and the height value rising or falling from the 0 height point is the relative height value. The way for resetting the altitude value is to press and hold the ALTI/+ button until 0M is displayed at the bottom of the screen, and then start to move, and the relative altitude value of the move will be displayed on the screen. Press and hold the ALTI/+ button again to switch back to the actual height value. Weather forecast: It can predict the weather conditions in the 12 to 24 hours when it is turned on, and the range is 30-50KM. 1. Long press the SET button for 2 seconds, 24Hr flashes, press the ALTI/+ button to switch between 24Hr or 12Hr 2. Press the SET button to enter the time setting, at this time the hour digits flash, press ALTI/+ or - to set the hour value 3. Press the SET button to flash the minutes, press ALTI/+ or - to set the minutes 4. Press the SET button to flash the calendar year number, press the ALTI/+ or - button to set the year value 5. Press SET button to flash the calendar month number, press ALTI/+ or - button to set the month value 6. Press the SET button to flash the calendar date number, press the ALTI/+ or - button to set the date value 7. Press the SET button to flash the temperature unit Celsius, press the ALTI/+ button to switch between Celsius or Fahrenheit 8. Press the SET button and the air pressure unit flashes, press the ALTI/+ button to switch to the air pressure unit /inHg/mmHg 9. Press the SET button to flash the height unit M, press the ALTI/+ button to switch between the height unit M or FEET 10. After the setting is completed, press HISTORY to exit the setting state, or automatically exit the setting without doing any operation within 10 seconds colour: Black grey Material: ABS size: 9 x 5 x 2cm Package Contents: 1 x altimeter barometer 1 x English manual 1 x CR2032 button battery (not included)