The Voltage Tester Pen Is Used For Testing The Circuit And Distinguishing Whether The Object Is Electrified; The Higher The Voltage, The Brighter The Neon Tube Light. When Using The Voltage Tester, Please Insert The Screwdriver To The Bottom, Hold The Insulated Handle With The Thumb And Middle Fingers, And Hold The Cap At The End Of The Voltage Tester With Your Forefinger.