Automatic switch-off - After approx. 3 minutes without operation or signal detection, the voltage detector is switched off automatically to save electricity. This can extend battery life. [Non-contact AC Voltage Tester]: This test pen has NCV sensor, you can detect the presence of AC voltage by simply pressing the power switch and bring the probe of the test pen close to the power socket or live line. [Alarm function]: When the AC voltage is detected, the sensor indicator lamp of the tester blinks. The test pen lights up the corresponding signal strength indicator depending on the detected signal strength. Two red lights, two green lights and one green light respectively indicate high, medium and low signal strength, and the buzzer sounds different alarms. [Adjustable Measurement Range]: The HANMATEK non-contact AC tester can adjust the gear in 9 steps, and the detection range can be freely switched between 12-1000v and 90-1000v. [With Lighting Function]: With an LED flashlight function that is convenient for use in the dark, it can also be used as an emergency light in an emergency. [Auto Power off Function]: If there is no operation within 3 minutes and the test pen does not detect the AC voltage, the test pen will shut down automatically. The package is equipped with a contactless stylus, a manual, and two 1.5V AAA batteries.