FrSky FLVSS LiPo Voltage Sensor with Smart Port
With a crisp OLED display, it can either be used as a stand alone voltage checker, or you can unlock it's full potential by connecting it directly to compatible Smart Port receivers, such as the X4R, X4R-SB and X6R.
With live telemetry data of each individual cell, you will never be uncertain about the status of your battery again!