... range, water proof design, can connect directly to DVR, VCR, active loudspeaker, headphone, soundcard of PC and anywhere CCTV installed, the maximum ... 3 x 0.5mm2 RVVP cable, 4 core phone line, network twist line, etc.11.Built-in over-loading protection and ... circuit.12.Pre-amplifier, directly drive DVR, VCR, headphone, loudspeaker etc.13.Excellent voice experience, widely working temperature: -25~75 ...