This XmartO high gain mini microphone 2 pack is the best for CCTV applications. Power in and power out design allows the microphone to share the same power source with the camera. No additional power adapter needed for the microphone. Specifications * Frequency Range: 100 ~ 5500Hz * Working Voltage: 6 ~ 12V DC * Audio Output: RCA * Range: 5 ~ 60 square meters Package * 2x Microphones for Security Cameras How to get it work 1. Connect xmartO add-on microphone to the camera. Secure the microphone from rain or snow. 2. Go to NVR's main menu – System setting - CH setting - Encode setting, change Encode Mode to "AV Stream", save it. 3. Now you get audio from this camera. Note: You need to change Encode Mode to “AV Stream” for all channels that you have added microphones. How can you hear the voice? 1. Through the app, turn on audio on app, you can then hear the voice from your phone. 2. Plug a headphone to the NVR’s audio output, you can hear the voice from the headphone. 3. Connect NVR to a monitor/TV via HDMI cable, you can hear voice on monitor/TV, as HDMI transmits audio. 4. Backup the videos and playback them on computer, you can hear the voice. Features Pick up every sound with this super high gain microphone. Collect audio evidence is as important as capturing video evidence, this microphone is a perfect addition to any video security camera system. Share the same power source with the camera, no additional power adapter needed. Add this external microphone to your xmartO camera, you can hear and record voice