this jack to connect the USB cable on the reading light area is very convenient, charges the reading light not at a computer, but to any decision by the USB cable, the charging is done very quickly. Note that when the reading light is in "flight" mode, so wi-fi deactivated, it remains charged for very long, very economical compared to tablets that require a lot more energy. I think this decision is an essential complement to the reading light, and still enables more autonomy from the computer.