Klein Tools NCVT-1 Non-Contact Voltage Tester with Low Battery Indicator and Auto Shutdown Non-contact detection of voltage in cables, cords, circuit breakers, lighting fixtures, switches, outlets, and wires High intensity, bright green LED indicates the tester is operational and aids in illuminating the workspace When voltage is detected, a high intensity, bright red LED illuminates and a warning tone sounds Discrete digitally controlled ON/OFF power button Auto power-off feature conserves and extends battery life