Ten years is a long time and that"s exactly why we used a battery that lasts just as long. Equipped with E-Data memory and 4 multi-function alarms, you"ll never miss a step. 10 Year Battery Life - Shock Resistant - 200M Water Resistant - Auto EL Backlight with Afterglow - E-Data Memory - Memory capacity: Up to 40 sets of data (when there are 7 characters per record) - Actual number of records depends on number of characters per record - Password protected - World Time - 29 time zones (27 cities), city code display, daylight saving on/off - 4 Daily Alarms & 1 Snooze Alarm - Countdown Timer - Measuring unit: 1 second - Countdown range: 1 minute to 24 hours - Auto-repeat Function - 1/100 second stopwatch - Measuring capacity: 23:59"59.99" - Measuring modes: Elapsed time, split time, 1st-2nd place times - Hourly Time Signal - Auto Calendar (pre-programmed until the year 2039) - 12/24 Hour Formats - Accuracy: +/-15 seconds per month - Battery CR2025 - Approx. battery life: 10 years - Module 2548 - Size of case/total weight 52.4 x 45.9 x 16.5mm / 58g