This is the Futaba R6004FF 2.4GHz FASST 4-Channel Micro Receiver.
* Designed for short range application such as indoor aircraft only
* Limited flight range of 300 ft (91.4m) maximum
* Compatible with standard size connectors only
* Easy one touch linking to transmitter
* Dimensions: 0.81 x 1.39 x 0.30" (20.5 x 35.3 x 7.5mm)
* Weight: 0.13oz (3.8g)
* Power Requirement: 4.0V- 8.5V (although this receiver can be used at
8.5 volts, Futaba recommends you follow the voltage specs of your servos).
* F/S and Battery F/S function (for channel three)
* Battery F/S Voltage: 3.8V
* Approximate range of 300 ft (91.4m)