This board allows a TBS Unify Pro (5V or HV/Race) and receiver to be mounted in a stack for a low profile and clean solution. The pads let you to solder your Unify to the mounting board. You can either use the plug that comes with the Unify or directly solder the wires to the pads.
There is the option to easily solder a FrSky D4R, X4R, or XM+ receiver, but you are not limited to only those receivers. Spektrum, Futaba, FlySky, or any other receivers are also compatible. Simply connect the Rx directly to the flight controller (ignore the receiver portion on the board) or connect the Rx to one of the header pins on the Unify Mounting Board and use the pads located on the side as intended. The solder bridge pads will still have to be used to select which headers you will be using.