Overview:8 in 1 Function: Digital altimeter, digital barometer, digital compass, weather forecast, time, calendar, thermometer, & backlight. The device is based on the technology of electronic bearing sensor & barometric sensor The digital altimeter is designed for outdoor use, the detachable string makes the digital compass a perfect h&-carry device for various outdoor activates it will give you backlight when you press any button in any time Altimeter: -700 ~ 9000m / -2300 ~ 29500ft Weather forecast History Altitude record: 256pcs records Compass: show bearing in degrees & cardinal point Thermometer: In oC / o F format Clock: In 12 hours or 24 Hours format Calendar Backlight Battery :by 2 x AAA batteries (include) Specification:1 x Altimeter 2 x AAA battery Weight Approx:109.5g Size Approx:4.8 x 1.1 x 18.3