An 18-litre volume means that this bag is best used as carry-on. It has a well-balanced construction with four wheels and it weighs just 1.7 kg, so it's a light little bag.
From Amazon
Trunki Children’s Ride-On Suitcase and Kid's Hand Luggage | Perfect Toy Gift for 3-4 year old Boys & Girls : Skye Spaceship (Glow in The Dark)
Luksusbaby.com
Trunki Skye the Spaceship