Non-Contact Voltage Detector- Insulated voltage detector housing ensures safety. Testing can be performed without physical contact, and isolated operation ensures safe testing. Portable Pen-Shaped Design- The voltage detector stylus is designed in the shape of a pen with a pen clip. It easily clips into your pocket and many other places, allowing you to keep it handy during repairs, making your job easier. Adjustable Sensitivity - The sensitivity is adjustable for more sensitive and flexible measurements. Press the S button for 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 to suit your needs. It meets many needs in residential, commercial and industrial environments. Audible Alarm and Security Lighting - Distinguish what is live from what is not by different frequencies of the alarm sounds. The higher the voltage, the higher the frequency of the audible alarm and the frequency of the LED flashing. The white LED flashlight helps illuminate the work area in the dark. Note- Range: 12-1000V AC 50/60Hz EN61010-1/1000V. The Volt pen requires two AAA batteries to operate, for shipping safety, our pens do not include batteries.