The HDMI output module is for phantom Series. DJI have upgraded the phantom 3 by adding the HDMI output. You can now connect FPV goggles and then you can view live HD image from phantom 3 camera. Additionally the module also provide USB type port through which you can easily connect mobile device with it.
One of the important thing to be noted is that advanced and professional models of phantom 3 does not compatible with phantom 3 standard. You can easily switch the data on/off from rear DJI GO app module that is mounted at the back of the remote controller