... Over-loading protection, Lightning proofAudio Preamp Build-inOutput Connector Power+, Audio and GND Cable 3 x 0.5mm2 RVVP ... monitoring microphone.*Low noise, Low echo, clear speech, low price.*Built in digital audio disposal circuit , two step dynamic de-noise disposal ... cable, 4 core phone line, network twist line, etc.*Built-in over-loading protection and lightning proof circuit.*Pre-amplifier, ...