Works flawlessly. Acoustics will only work with an internal microphone with the EOS 5D M3. When shooting movies via external Micro Severe radio hum in the headset. Tried with three Micros. Then better yet battery operation, at least for video shoots. Since funzen the external microphones. However, the camera's internal Micro funtioniert perfectly even with the power supply. For longer shoots definitely great if you do not want to change the batteries every few hours