Electro-luminescent backlight, automatic with afterglow Light powered - no batteries to change - when fully charged has a 5 month power reserve. Low-temperature resistant (-10°C/14°F) Digital compass: Measures and displays direction as one of 16 points with a range of 0° to 359° in 1° units and has an abnormal magnetic field detect function and also bidirectional calibration and northerly calibration function Altimeter: Measuring range: -700 to 10,000 m (-2,300 to 32,800 ft) in 20 ft units (5m). Takes auto memory measurments storing up to 40 sets of data, each including altitude, month, date, time. Reference altitude setting and altitude alarm. 1-second stopwatch, coordinated with altimeter, measures elapsed time, split time, 1st-2nd place times Barometer: Display range: 260 to 1,100 hPa/mb (7.65 to 32.45 inHg) in 1hPa/mb or .05 inHg units) and atmospheric pressure tendency graph. (Ability to select between hPa and inHg units) Thermometer with a display range of:-10 to 60°C (14 to 140°F) in 0.1°C (0.2°F) units (Fahrenheit or Celsius is user-selectable) Duplex LCD Daily alarm Hourly time signal Battery power indicator Power save function (automatically disables LCD when the watch is left in the dark for 30 minutes) Auto-calendar (to year 2039, no auto day of week setting) 12/24-hour format Regular timekeeping: Hour, minutes, seconds, pm, year, month, date, day Accuracy ±15 seconds per month Size of case: .57.0 x 52.0 x 14.8 mm Weight: 77 g