Casio - Front-Facing Twin Sensor Design - GDF100-4 - This totally new design for G-Shock comes packed with altimeter, barometer and thermometer, plus a powerful collection of additional features. Its design has been carefully crafted to incorporate a number of basic elements that reflect G-Shock's unique individuality. Shock Resistant - 200M Water Resistant - LED Backlight (Super Illuminator) - Altimeter - Barometer - Thermometer - World Time: 31 times zones (48 cities), city code display, daylight saving on/off - 5 Daily Alarms - Hourly Time Signal - 1/100 second stopwatch - Countdown Timer - Full Auto Calendar (pre-programmed until the year 2099) - 12/24 Hour Formats - Button tone operation on/off - Accuracy: +/-15 seconds per month (with no signal calibration) - Battery: CR2025 - Approx. battery life: 5 years - Module: 3255 - Size of case/total weight: GDF100 55.0 x 51.5 x 17.2mm / 69.2g