The Flex Runners are meant to be slip-on but are impossible for my 3yo to manage alone, and honestly not even that easy for me to get on him. These, however, are the opposite. He sat down and put them on himself IN THE STORE without any instructions. The previous reviewer said the velcro seems to be on backward (it pulls to the inside of the foot rather than the outside--which is admittedly counter-intuitive for adults who have been doing it the other way their whole lives). But I think this actually makes fastening them easier and more intuitive from a gross motor standpoint, and my son's feet don't hit each other when he walks so it hasn't been an issue. He has been super comfortable in them--and he's a Crocs kid, so that's saying something.