This is Futaba R404SBS-E 4-Channel F-4G-2.4GHz System Diversity Internal S.BUS2 Receiver or F-4G Systems Only e.g Futaba 10PX

Feature:
For Futaba R404SBS-E
Material: Plastic
Color: Black
Special Functions: Diversity Antenna

Specification:
Receiving frequency: 2.4GHz band
Channels: 4 + S.BUS
Telemetry Receiver RF power output: 2.2 mW EIRP
Power requirement: 3.7 V~7.4 V battery (Dry cell battery cannot be used.)
System: F-4G system/S.BUS2 system
Size: 25.5x20.7x10.6mm (includes a 30.5mm high antenna housing)
Weight: 7.2g 

Include:
Futaba R404SBS-E 4-Channel F-4G-2.4GHz System Diversity Internal S.BUS2 Receiver (1pc)