Both.
We have one of each of ours, perfect to carry all the bit they want cardies/jumper/ PJ if its a late flight, sweet, drinks, crayons etc.
They have fun at the airport if the flight is delayed, Trunki races are a big thing and others join in make the waiting better no winging. It also makes the long walks faster as i can pull them or the scoot off the miles go quicker than on foot.
We also use them when its raining at home. There are loads of game you can play.
HTH
x
Edit to add They cant go in the hold they are hand luggage only. They will not withstand the hold pressure unless unlocked and open!!!