¡ì the high sensitivity of high-fidelity acoustic¡ì Built-in AGC gain audio circuit¡ì Import amplifier ICs, coupling capacitance¡ì 2mm pinhole design¡ì Japan's imports of gold-plated capacitor microphone¡ì Dynamic closed-loop noise reduction circuit10 to 200 m2Impedance 600 ohmsFrequency 20 ~ 20KhzPower 9 ~ 12VDCSize 75 * 75 * 23mmFor HaiKang, Dahua DVR device