Adjustable sensitivity low noise mini shape sound audio monitor, super high sensitive mini microphone capturing audio evidence. | Sound pickup use the high fidelity and low noise process chip. Clear voice, low noise high fidelity, applies to a variety of situations. | RCA for audio output, 2.1mm center DC plug for power input and output. | Audio Monitoring Range: 10-150 square meter, volume adjustable. | Appropriate places: banks, offices, hospitals, letters and visits offices, border inspections, front desks, prisons, interrogations, airports, classrooms, examination rooms, companies, museums, auction houses and other places that need to restore sound and record history.