These pocket - sized AC line voltage Detectors/testers have a nonconductive outer surface for user safety. Simply touch the tip of the Tester to an Outlet, terminal strip or cord; If the tip glows red and unit beeps, there's voltage in the line. Ideal for quick checks for energized circuits or ground faults. Available for sale in the United States and Canada only. Always on-uses special low-power circuitry to sustain battery life and for added dependability what's included: 2 AAA batteries detect voltage quickly and easily - without contacting metal! detects voltage without metal contact fits in shirt pocket for convenience all outer surfaces are nonconductive for safety.