From 3 to 5/1/2 my now almost 7 yr. old was in a harnessed Frontier 80 or a Marathon 65. Her travel seat was a Safegaurd Go (now Safety First Go). My almost 3 yr. old will be in a Blvd 70, Roundabout 55, and or the Frontier 80 (if she outgrows the RA55). She will use the Safegaurd Go as well.