Detects voltage in tamper-resistant and conventional 15Aand 20A, 120V outlets. Patented automatic self-test verifies the integrity of the unit. Bright LEDs flash and audible alarm sounds if voltage is present. Silent-mode feature for use in quiet settings. Safe, non-contact voltage detection. use to detect voltage in outlets, lighting fixtures, circuit breakers, wires, and cables or to find a break in a wire. Automatically turns off after five minutes of non-use to conserve battery life. Low battery indicator. Designed and assembled in USA. (2) 1.5V AAA batteries included. Lifetime Warranty.