Powerbanks must be carried in hand luggage on planes. So far, no one has ever wanted to inspect them on my flights. It's basically just a battery like in any laptop.
The powerbank works with laptops, and is probably enough for more than one charge for current laptops.

However, the powerbank cannot be used and charged in parallel at the same time, like almost all powerbanks.
Also note that the USB ports are deactivated as soon as the socket is switched on - but I'm not 100% sure about this - so charging a mobile phone via USB and a laptop via the socket doesn't work, but of course you can charge the phone via the laptop. The socket only works when the power switch is pressed for a few seconds, then a green light also lights up.