This works on any LG Smart TV from the 2012 models onwards. And the LG Home Theater System.
In using the app, there will be a about 2 to 3 seconds of latency. So this mirroring is not suitable for gaming.
However, it is very suitable for watching movies, giving presentations, watching photos, and much more!
The quality of your experience will be dependant on the quality of your local network. Some tips to enhance the experience:

- Preferably, connect your TV by LAN cable to your router.
- Use an "ac" router. If you don't have one, then an "n" router.
- Try not to overload your wifi network by moving big files around while you are mirroring.

How the app works:
After launching the app, you will see the app icon appearing in the top bar of your Mac. Click on the icon and you will see a list of options:

DEVICES:
Here we scan your home network for connected LG Smart TVs. When a TV is found in the same network as your Mac, it will be listed here. To start mirroring, select the TV from this list.

DISPLAYS:
Under Displays, you will see all your screens. The primary screen of your Mac, or, when you have another monitor connected, you will see that screen as well. Please select the screen that you would like to have mirrored on your LG TV.

Enable Audio: you can choose whether you would like to hear the audio on your Mac or through the speakers of your LG TV.

NETWORK QUALITY:
When you are experiencing performance issues with the app, it might be because your local network is not coping with the video data that we are sending from your Mac to your TV. You can select a lesser quality network and try again.
 
Compatibility: OS X 10.10 or later, 64-bit processor
Home Page - https://itunes.apple.com/us/app/mirror-for-lg-tv/id1152966194?mt=12