The photo that was posted on Twitter wasn't part of a Guard Lite, or even an add-on, but a Wifi sector antenna with a base station attached to a wall under the eaves of a building.
The antenna/base station combo looks to be the Ubiquiti AirMax AM-2G15-120 antennas with one of their Rocket base stations:
You can buy one on Amazon, but this was likely purchased and installed by a pro: