Question Moving from Radians, Frontier vs Defender vs...?


New member
My twins are almost 6yo and very tall. I would still like to harness them as long as possible and, due to safety, would probably prefer high-back booster.
The seats will need to go in a Prius, a Camry (or similar sedan), and 2nd row Sienna (mini-van).
I understand that the Harmony Defender is narrow like the Radian, but 2 inches less on the top shoulder harness height (and only 1 inch more than current Radian). Also it becomes backless booster, but do I want that?
Seems quite a bit cheaper given my kids' future in seats (though it may be at least a couple years before they're 4'9", they're about 4'4-4'5 now). I do like the safety features of the Frontier, but so bulky.
Recommendations? Other thoughts?


Admin - CPST Instructor
Staff member
At their age, a harness is optional if they'll sit properly.

They should likely be using a booster for another 4-6 years.

The Defender has 1" higher top harness slots, turns into a much taller booster, then yes, turns into a backless. You'll want a backless booster for after they outgrow a high back but before they fit properly in the seatbelt. If you got something like the Frontier you could, in theory, go from high back to seatbelt alone, but most kids don't want that, and at 9-11 years old or so, a backless is a perfectly safe options, so I'm willing to hear a child's opinion more on it at that age.

If they still fit in the Radian at their extreme height, they must have all of their height in their legs. So a Defender would work. Most kids have long outgrown a Radian at 53" tall, though. If you do want to harness such tall kids, the Britax Pioneer/Frontier/Pinnacle are the tallest.



New member
Thanks for the info.
So mine do have a lot of ht in their legs, but I just measured them and they're about 18" to top of shoulders (seated on carpet), so really at the end of Radian use.
I also measured their growth since we moved into this house and they have grown over 2.5" in the past 9mos alone (again, likely more in legs). I don't know the average growth of torso height per year in kids their age. They are usually about the height of a child at least 1-2yrs older.
They are young twins (still 5yo) so harnessed is really better for them (behavior-wise), I would prefer another year if possible.
Given this rate I can't imagine they would still need a booster past 9yo, but my concern is them outgrowing the high-back of the Defender before they turn 7yo!
And what exactly is the bottom line on high-back vs backless in terms of boosters? Age- or size-related?
Thanks again!
- Soni


Admin - CPST Instructor
Staff member
Most kids need boosters to 10-12, even tall ones. :) The high back of a Defender goes to about a size 10 shirt, to give you an idea, then they use a backless until they pass the five step test. A backless is used when a high back is outgrown, so kind of age and size. If there was a small nine year old who wanted a backless and got a good fit, I'd be more ok with that than I would be with a six year old who hadn't outgrown a high back yet.

The Defender's highest harness height is 18.5", and 2.5" a year is quite normal. For every 2-3 overall inches, about 1" of torso growth is expected. So the Defender should get them the time you want for the harness, then high back, then backless until they pass the five step test, so about the next five years or so without an issue.



New member
So I guess it seems you're saying they will likely need something at least another 4yrs, the difference would be that Frontier they would go longer high back and then may need to buy separate backless boosters, vs Defender they would have to move from harness sooner and then move into backless sooner, but at least don't need to buy anything anymore?

Expense is probably the biggest issue at this point just because I'll need to buy at least 2 new ones (possibly up to 4). I assume once in booster mode, moving from car to car is not a big deal like it is with an installed seat, is that correct (was also hoping that Clicktight would be easier too, because usually I don't move seats)?

And again, about the backless issue, I was thinking it was recommended to go high-back as long as possible, or is that more with younger kids?

Thanks, Soni


Admin - CPST Instructor
Staff member
I'd use a high back until at least eight or older, but there's nothing in that based in science. More that's when a lot of kids start being about the size in a backless booster when the side curtain airbags will be helpful.

Backless boosters start at $13, so even people who are generally on a tight budget can save for it in a few months.

Both the Defender and Frontier will work well for you. As boosters, both can use the lower anchors so they're not projectiles when not in use. But if you're moving them to new cars every time, then the children will be in them so that's a step that can be skipped.



New member
I'm not sure if this is true, but I've heard you can take the memory foam off the radian (below the seat cover), if so that may give you a little more time in their current seats. May e in6 month they'll be ready for a high back booster. Then you can get two really nice tall boosters for much cheaper.

Also, there is two red frontiers on Amazon right now that are open box.

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