This 12-600 VAC Adjustable Circuit non-contact Voltage Tester features on/off adjustable sensitivity that detects the presence of AC Voltage from 12-Volt - 600-Volt without contacting wires. It includes an audible sensor and flashing visual sensor to indicate voltage. A built-in safe test feature assures batteries are operating properly. Operates from 2-LR44 1.5-Volt batteries (included). Applications include testing doorbells, low voltage lighting, outlets, switches, electrical panels and light fixtures.