This is the Futaba R304SB T-FHSS 4-Channel Telemetry Enabled 2.4GHz Receiver
NOTE: This receiver is NOT compatible with 2.4GHz FASST, FASSTest, FHSS or S-FHSS non telemetry systems.
Specifications:
Dimensions: 1.54x1.02x0.39" (39x26x10mm)
Weight: 8 g (0.28 oz)