Greenlee® voltage detector, non-contact self-testing, series: GT, 50 to 1,000 VAC, led/audible alarm indicator, 1.5 VDC AAA battery power source, thumb switch, safety rating: cat IV 1000 VAC, green. The Greenlee® GT-12A voltage detector is intended to check for the presence of AC voltage, signaling the user with an intermittent tone and flashing led. The tone can be disabled using the smart on/off button. The GT-12A has a self-test feature that continuously tests the integrity of the entire unit including the antenna. The GT-12A also features low battery indication and an auto power off feature. Greenlee® GT-12A Non-Contact Self-Testing Voltage Detector, 50 to 1000 VAC, LED/Audible Alarm, Cat IV 1000 VAC