G.D.
Hi,
I just bought the Britax Frontier for my 4 1/2 year old since my 16 month old needed the Britax Marathon (from the 4 1/2 year old). We absolutely love the Frontier! It is a car seat/booster seat that offers a 5-point harness and converts to a full-back booster with cup holders and an adjustable head rest. My daughter loves it as well. The seat actually sits lower than the adjacent Marathon and is extremely comfortable (my daughter always falls asleep while riding). I highly recommend the Frontier...love Britax.