Features: Automatic shutdown: When the test pen does not receive any operation within 3 minutes and does not detect the AC voltage, it automatically turns off. Acousto-optic discrimination of Live or Null Wire: Live Wire Testing: Connect the sensing end of the test pen to the object to be tested. If the analog bar is within 6 grids, the slow rhythm buzzer will alarm and the display will be green and backlit.indicating that the test is a LIVE WIRE. Null Wire testing: Put the test pen test head close to the object to be tested, such as the analog bar, the fast-paced buzzer alarm, the display is bright red backlight,indicating that the tested line is Null Wire. This product has more comprehensive functions: Large Range Measuring For testing AC Voltage Recognition of Live/Null Wire Triple alarm of sound, light and screen Energy-saving and bright LCD screen High and Low Voltage Signal Indicator Buzzer alarm - loud and sensitive White LED lighting - - energy saving, convenient Auto power off Switch key Good Sensitivity of NCV Sensor Technical Specifications: AC Voltage: 12V-1000V Frequency: 50Hz / 60Hz Alarm Mode: Sound and light alarm Electric Torch: LED illumination Low-voltage indicator lamp: Yes Power Source: 2 x 1.5V AAA Batteriesnot included Security Level: CE CAT. III 1000V / CAT. IV 600V Service Temperature: 0-40 degC Storage Temperature: -10-50 degC Altitude: Safety Compliance: CAT.III 1000V CAT.IV 600V Package List: 1 x Non-contact Voltage Tester Compact Pen 1 x User Manual