MA and RN are both 17, but the RN is so much more upright it lasts kids about a year longer than the MA. Britax says the top torso height for the MA is 16, I halfway think that's so people don't buy it for a kid with a torso height taller than that and then gripe that it didn't fit long enough
. Wendy has a picture of a mysterious RN that has 18 inches with the cover on....
I think 17 is fine for most kids... that was 6.5 for my kid, maybe not Unityco's or AuntietoAvi's kidlets who were too tall at 3-4, but those are big guys... :twocents: