The Triplett ET400 combines a Non-Contact Voltage and Phase Sequence Tester. It has dual AC voltage ranges: 12 to 1000V and 100 to 1000V with high sensitivity that allows it to detect low voltage AC wiring commonly found in doorbell circuits, thermostats, control circuits, and video surveillance camera power. In addition, you can quickly determine the correct phase wiring sequence (L1, L2, L3) for 3-phase system installation. It features a built-in flashlight and CAT IV 1000V safety category. Includes (2) AAA batteries.