... 3,AV and DC jack pinhole monitor china factory, Mini Audio monitor with 160metres monitor range,0.2g,14x4.2mm Features1, Suitable ... square meters. 3,High sensitivity, low noise, low distortion, small size, low voltage, small power consumption( 4pcs of 3A batteries can ... be used in highway toll station when it is connected with a wireless repeater.6,Cable connection, red-- power supply black ...