... • Fully functional self-testing: sensor, integrity of battery and circuit, acoustic & visual & vibration three-stage ... high alarm, multiple gas alarm, sensor alarm, battery low alarm, prompt tone, automatic shutdown alarmAcoustic AlarmVariable- ... measurement range calibrationContinuous working period2*alkaline battery: 16~18 hours2* nickel-hydrogen rechargeable battery: 14~16 hoursInitial Charging ...