Attaching this antenna booster will increase the range distance significantly.  The reflector on the transmitter will collect huge amount of signal from the drone, thus it can receive very weaker signal comparing to the transmitter without the reflector  and as a result the distance for reception will increase.

Similarly when transmitting, majority of signals are directed towards the drone as a result the drone will receive stronger signal, thus the distance range increase.

Antenna Range Booster  for DJI Phantom 3, 4 and Inspire 1,2