FlySky FGr4 2.4GHz 4-Channel AFHDS3 Receiver. This receiver operates on the 2.4GHz frequency band and utilizes the AFHDS3 (Automatic Frequency Hopping Digital System 3) protocol, which ensures a stable and interference-free connection. It is lightweight and compact, supports four channels, and operates on a wide voltage range, all of which make this receiver the perfect match for compatible AFHDS3 capable transmitters.