HUACAM HAS04 High Sensitive Audio External Microphone for CCTV Security Camera CCTV DVR Surveillance System,Volume can be Adjusted Pick up every sound with this super high gain micro audio system, RCA for audio output,2.1mm center DC plug for power input Preamplifier used to increase a microphone's low output voltage to a stronger usable level Super high sensitive mini microphone capturing audio evidence for security camera system Monitor range: 60sqf -1600sqf. Current consumption: 20mA,Volume can be adjusted