Futaba Rx 6004FF Micro 2.4G FASST

SPECS:    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)