Barometer &amp; Altimeter: The air pressure value on the screen corresponds to the air pressure at the current location. The height value on screen is the sea level of the current location. Press the [ALTI/+] button to toggle ;using the ;altimeter and barometer.Relative Altitude: Monitor ;altitude ascending or descending from ;a certain location or ;relative altitude ;a mountain or ;an object, etc. Weather forecast: In addition to detecting ;altitude, the barometer also helps predict the weather for the next 12 to 24 hours based on changes in barometric pressure. The effective range is 30-50 km.History altitude record: Press [HISTORY] button, you can view the history altitude and air pressure records. It will display the most previous record in this mode, then you can press [ALTI/+] or [-] button to view history records forward or backward. It can record most 256pcs records, the records distance is five minutes and you can change the distance from 1 to 60 minutes if you hold [HISTORY] button for 2 seconds.Design; Energy saving: When you do not want to use the device, press and hold the [SET] button for 5 seconds, the device will stop all displays and enter sleep 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. Product Description Materials: ABS Historical altitude record: record of 256 pieces Thermometer: Celsius/Fahrenheit format < p> Clock: 12 hour or 24 hour format Calendar, backlight Design; energy saving: start automatic altitude measurement Power:1 x 3V CR2032 battery (not included) ; Note: Due to manual measurement, the size may have an error of 2 cm/1 inch; Due to different displays and angles, the color and size may be slightly different, thank you for your understanding! Note: The data is all measured manually, please allow 1-3cm error, due to the difference in light and display, there will be a certain color difference, the actual object received shall prevail.