The boya by-mp4 is a simple and functional 2-channel audio adapter. The by-mp4 can be connected to a smartphone, dslr, camcorder, and pc using the included 3.5mm trrs cable and 3.5mm trs cable. The by-mp4 provides you with a simple solution for using audio mixing and dual-mic mounting. The by-mp4 has three mounting shoes on which various accessories such as microphones, radio receivers, led lighting, etc. are mounted. No battery required you can use the by-mp4 without batteries. The boya by-mp4 works with the phantom power of the camera. Use boya by-mp4 you can use the by-mp4 as follows: at the stereo input you connect a shotgun microphone, which you attach to the top of the by-mp4. Connect a lavalier microphone to both mono inputs. These can also be wireless microphones. You can check the receivers on the left and right hot shoe. The stereo mono button allows you to switch between the microphone and the sound of both lavalier microphones. Since the sound of the mono channels is a separate track, you can edit both separately in edit.