SIENOC LED Light Non-contact Ac Electric Voltage Tester Volt Alert Pen Detector Sensor 90-1000v 1 100% Brand new and high quality 2 Safe and easy-to-use 3 The voltage detector designed for electrical testing 4 Small and compact pen design for easy carrying 5 Voltage Sensitivity: 90~1000V AC (never test the voltage which is more than 1000AC) 6 This instrument is only used to judge whether the conductor is live or not. 7 Power by: 2 x 1.5V AAA batteries (Not included ) 8 A necessary tool for everybody who works with electricity 9 Ideal for testing AC cables, circuit breakers, wall sockets, junction boxes, fuses, etc. 10 All outer surfaces are non-conductive for safety Use Method: Touch the wire with the pen tip. If the red indicator lights up, together with buzzer sound, it means voltage exist. If the light and sound are week, please replace the batteries inside.