Voltage Sensitivity: 90 ~ 1000VACBandwidth: 50/60HzNormal Indicators: Beep and flashing LED indicate the presence of voltageBattery Indication: The LED will not flash if the battery is less than 2V.The beep sounds will still have but may be weaker.Silent Indicators: LED flashing only, it could save batteryAuto Power Off: Around 3 minutesPower: 1.5V Battery (AAA) x 2