Maximum volume at minimum weight (kg so much to pack) was what I was looking specifically for flying and take this as hand luggage. Previously tested: Ryanair, Vizz-Air, Lufthansa and at various airports. Result: always come up OK as hand luggage, never even a hint of doubt. My daughter had therefore already been borrowed and absolutely successfully completed a Ryanair flight. The doubts about dimensional tolerance described by others I had experienced in practice as irrelevant. This luggage backpack-trolley suitcase miracle is indeed made of soft fabric and can be temporarily filled in regardless of Maßkontrollfach. I like the baggage hold and after each travel more. Few weeks ago I had a flight abroad, which I continue immediately with train (for ticket hire me) and then had to travel by bus .... And finally, 20 min. on foot. It was just perfect that I was able to transform my luggage back and forth between rolling suitcase and backpack.