Non-Contact Voltage Detector- The insulated housing of the voltage detector ensures safety. Testing can be performed without physical contact and the insulated operation ensures safe testing. Portable Pen-Shaped Design- The voltage detector pen is designed in a pen shape with a pen clip. It easily attaches to your pocket and many other places, allowing you to keep it handy during repairs, making your work easier. Adjustable Sensitivity- The sensitivity is adjustable for more sensitive and flexible measurements. Press the S button to get 3 levels of sensitivity adjustment. One beep indicates low sensitivity, two beeps indicates medium sensitivity, and three beeps indicates high sensitivity, allowing you to adjust the sensitivity according to your needs. It meets many needs in residential, commercial and industrial environments. Audible Alarm and Safety Lighting- Distinguish between live and dead voltage by different frequencies of alarm sounds. The higher the voltage, the higher the frequency of the audible alarm and the higher the frequency of the indicator light flashing. The white LED flashlight can illuminate the work area in the dark. Note- Range: 12-1000V AC 50/60Hz Note: Two AAA batteries are used for power supply (not included) and LED lighting for easy use after power failure. AC Voltage Detection: The tester probe is inserted into the power outlet or near the live wire. When the tester detects the AC voltage signal, the induction voltage signal indicator flashes. According to the detected signal strength, the tester lights up the corresponding signal strength indicator (high, medium and low). At the same time, the hive emits alarm sounds of different frequencies. When inducing to an AC voltage signal, the signal strength indicator L (low) flashes; when inducing to higher AC voltage signal, the signal strength indicator M (medium) is long; when inducing to the highest AC voltage signal, the signal strength indicator H (high) flashes 3 times. 1. Automatic Shutdown Function. When the voltage detector pen has not been used for about 5 minutes and no voltage signal is detected, the pen will automatically shut down. 2. Low Power Alert. When the battery voltage of the pen is lower than 2.6V, the power indicator of the pen will flash 3 times and automatically shut down after a sound. AC Voltage Range: 12-1000V Frequency: 50Hz / 60Hz Alarm Mode: Audible and visual alarm