The child restraint system CASUALPLAY BACKFIX I-SIZE does not require a seat shell in the car, thus providing safety as well as comfort. This design allows children with a height of 100 to 150 cm to sit directly on the soft car upholstery and have a greater distance to the interior parts of the vehicle than they would have on a child seat. The side impact protection and the Isofix attachment system for easy installation are further product characteristics.