SEECOM High Sensitive Preamp Tiny Spy Camera Microphone Audio Pickup Device Kit for Security Camera Sound Voice Monitoring Recording with 60Feet Cable and Power Supply Super high gain mini microphones capturing audio evidence for security camera system Preamplifier used to increase a microphone's low output voltage to a stronger usable level Built in on board IC preamp, low noise, high gain and auto level adjustment Pick up every sound with this super high gain micro audio system Widely used in banking, finance, shopping malls, prisons, justice, classrooms, conference rooms, industrial production, military areas, and many other places