... ,Booking Rooms,Cell Monitoring etc.. S.Tradio audio surveillance kit for law enforcement, such as:Police Interview Rooms,Holding ... headphone, soundcard of PC and anywhere CCTV installed, the maximum wire transmit distance can reach 3 Km(shield cable is required ... -in over-loading protection and lightning proof circuit.11.Pre-amplifier, directly drive DVR, VCR, headphone, loudspeaker etc.12.Excellent ...