2 nitrox mixes to 100% oxygen, deep stop with countdown timer, intuitive user interface with step back, time, date & temperature. Audible alarms with user acknowledgment, gauge mode with run-timer, history mode and 24 dive/99 free dives on-unit log book. Last dive display: max depth and dive time, diver-replaceable battery with data retention, user upgrade able firmware. Power: CR2430 Lithium battery, operational depth: 330' (100 meters) - altitude adjustable: 3, 001' to 14, 000' (916 to 4, 200 meters). Dual time display and daily alarms, backlight for night or low light conditions, 4 operating modes: watch, norm, free dive and gauge.