This is the Traxxas 2218X Micro TQ 2.4GHz 5-Channel Receiver with Traxxas Link
2.4GHz technology Traxxas Link automatic model recognition software allow previously bound receiver to be recognized by transmitter and recalls all settings when specific receiver is switched on.
One Micro TQ 2.4GHz Receiver with Instruction Sheet
Length: 1.5" (37.5")
Width: 1" (25.5mm)
Height: 0.65" (16.5mm)