This external hard drive is powered directly from the computer: this is very useful for trips away from all sources of 220 V (in nature, in places where the power supply fails, ...) !!! It is therefore the perfect complement to any notebook, but it is of course also usable at home on stationary computers ... so Ideal for storing files there anywhere we want to have immediately at hand !!! Icing on the cake: the price is to my knowledge the cheapest in its class, and Amazon.com has delivered me over Marseille in just two days: bravo and thank you !!!