4700uF 10 Volt capacitor for receiver voltage stablisation. 
High current demands from the 290G1 and similar models as well as high power rudder servos can cause voltage in the receiver to drop below the receiver's minimum. This causes the receiver to hesitate which is in turn causes the SmartWinch to also hesitate. The addition of this capacitor in the receiver in most cases completely prevents these annoying "glitches".