Safe and Convenient, The Voltage Pen Tester Detects Voltage in a Non-Contact Way, So Do Not Worry about There Could be any Possibility of being Shocked by the Electricity High Efficiency, As Long As Voltage is Detected, the Led in the Tester Pen will Shine Multifunction, Easy to Use, It Also Acts as an Emergency Flashlight which can Illuminate the Working Area, You can Use the Non Contact Voltage Detector in Circuit Breakers, Lighting Fixtures, Switches, Outlets, Wires and Anywhere You Need it.