I struggled to find a harnessed booster that has enough height to be the only booster my child needs until able to safely sit in a standard car seat. This has been a great find. Harness on our almost 5 year old (average height) has another slot to go up so some time in the harness still, and then there is a huge amount of height with the standard booster with lap/sash belt. Also good head support/wings for side impact and also when they fall asleep. Great service from Winkalotts too.