This is the Futaba 2.4GHz R3001SB 2-Port T-FHSS S.Bus Telemetry Receiver.
T-FHSS 2.4GHz receiver for aircraft
Standard PWM (CH3)/S.Bus port and an S.Bus-2 port for telemetry
sensors and other devices requiring S.Bus setup such as specific
gyros and servos
Channel Mode Settings; Mode A Mode B
3/S.Bus CH3 S.Bus
Dual antenna diversity
One year limited warranty through Hobby Services beginning at date of
R3001SB 2-Port T-FHSS S.Bus Telemetry Receiver
Dimensions: 0.83 x 1.65 x 0.21" (21.1 x 41.8 x 5.3mm)
Weight: 0.15oz (4.2g)
Power Requirement: 4.8-7.4V
Battery FS Voltage: Sets from transmitter
S.Bus/S.Bus2 Port: The R3001SB can be used with up to 18 channels.
However, it differs according to the transmitter. An unused channel
is a neutral signal. The F/S setting channel at F/S/ is F/S/
position. Another, it is a hold signal.