The Klein Tools NCVT3 Non-Contact Voltage Tester, 12-1000V AC with Flashlight provides non-contact detection of AC voltage. The higher the voltage sensed, or the closer the tester is to the voltage source, the more LEDs light up and the audible indicator beeps at a greater frequency. Screw-thread battery cap with O-ring ensures protection against dust and water ingress. The included bright flashlight illuminates work area and may be used independent of voltage detection function.