Klein Tools RT390 Circuit Analyzer tests the wiring conditions at an electrical outlet and displays various readings on a large LCD screen. This analyzer displays AC line voltage, inspects GFCI and AFCI devices with time to trip device, and performs voltage drop tests at 12A, 15A, and 20A current loads. When monitoring, the background will turn red if the voltage drop is greater than 5%. Various buttons on the RT390 analyzer include a load button that tests 12A, 15A, and 20A to display percentage drops, a power/reset button, and an energized indicator that is bright red to show voltage. Klein Tools RT390 Circuit Analyzer has a detachable cord and comes in a pouch with 3x AAA alkaline batteries.