KKmoon Portable Multi-functional Digital Altimeter Compass Thermometer Barometer Green Backlight This multi-functional digital altimeter is ideal tool for camping, climbing or other outdoor use. It combines functions of altimeter, compass, thermometer, calendar, barometer, weather forecast and time display. Press the "ALTI" button to measure the height above sea level where you stand. Hold it for 3s, it measures the relative height. Press the "COMPASS" button, the arrow shows you the direction. Press the "SET" button to set date, time and temperature format.