... for outdoor usage >Built-in microphone for audio monitoring 2.4GHz digital wireless technology High definition and high frame rate ... 7" Transmission frequency ISM 2,400 MHz~2,483 MHz 4CH Receiving Sensitivity ≤-85dBm Power Adapter DC 12V/ 1500mA transmission ... gCamera:Transmission frequency ISM 2,400 MHz~2,483 MHz 4CH Receiving Sensitivity ≤-85dBm Power Adapter DC 12V/ 1500mA transmission distance ...