ah so the failsafe by itself still needs 4.8 volts to work properly?

and
"NO power, nothing functions... Fail-safe listen the control signal from the RX, when there is no signal for less than second the fail-safe initiates a hold or movement to pre-defined parameter. Once a signal is again recognized the fail-safe or hold is released and your driving again. This all can occur in less than a second... "


is this with an "inline" failsafe?
like if the power goes out in your car it sends the servo to a spot like full brake?