... microphone.*Low noise, Low echo, clear speech, low price.*Built in digital audio disposal circuit , two step dynamic de-noise disposal.*Special ... Over-loading protection, Lightning proofAudio Preamp Build-inOutput Connector Power+, Audio and GND Cable 3 x 0.5mm2 RVVP cableVoltage DC ... Material PVCSize 60mm × 22mmWeight 30gStandard CE I.TRADIO hidden,mini,built-in wall Audio Surveillance Microphone