Clek Fllo vs Diono Radian 3QXT

Buy the Clek Fllo if you need the narrowest shell and rebound control; buy the Diono Radian 3QXT if you want one seat to cover every stage. The Fllo's seating width is 16.9 in and it includes an anti-rebound bar, rear-facing 14-50 lb and forward-facing to 65 lb. The Radian 3QXT is 17 in wide — a tenth of an inch more, which is not a real difference in a car — but it carries on as a highback booster to 120 lb, where the Fllo stops at 65 lb forward-facing.

So the width comparison that brought you here is close to a tie. The decision is actually about two other things: whether you want an anti-rebound bar and the Fllo's rear-facing starting weight of 14 lb, or whether you want the Radian's booster stage and the option of the cheaper Radian 3R. Both are genuine three-across seats; the wrong question is which is narrower.

Published figures for both seats, plus the Radian 3R as the budget version of the same idea.

The 51 in figure on the Radian 3R is the most useful number on this page, because it is the one you can actually check. Measure the usable width of your own back seat between the door trim, and if it is under about 51 in, three seats of any kind will be a struggle. That measurement, not the product width, is what decides a three-across.

Two concrete advantages. The first is the anti-rebound bar, which limits how far the seat rotates back toward the vehicle seat in a crash. It is a feature you find on premium infant bases and relatively few convertibles, and the Fllo includes it rather than selling it separately. The second is the narrowest published seating width here at 16.9 in, which matters in the specific case of three seats in a genuinely narrow bench where every fraction counts.

The constraint to know about is the rear-facing start: 14 lb, not 4 or 5 lb. The Fllo is not a newborn seat. If this is a first baby you will need an infant carrier for the early months and the Fllo afterwards, which is a reasonable plan but a real extra cost — see best infant car seats. For a second or third child already past 14 lb, that restriction costs nothing.

The Radian 3QXT does more jobs. It starts at 4 lb rear-facing, so it works from birth, and it finishes as a highback booster at 120 lb — which on paper is one seat from the hospital to the end of the booster years, in a 17 in shell. For a three-across family that is a meaningful saving, because buying three seats twice is the actual expense.

The Radian 3R is the same width and the same basic steel-framed shape at a lower price, with a 5 lb rear-facing minimum and the same 120 lb booster span. It is on this page because for a lot of three-across buyers it is the right answer: if you need three narrow seats, three 3Rs usually beats one premium seat and two compromises. The trade is adjustment range and fabric quality rather than width.

• Buy the Clek Fllo if your child is already over 14 lb, you want an anti-rebound bar, and you need the narrowest shell available.
• Buy the Diono Radian 3QXT if you want one seat from newborn to the end of the booster stage in a narrow package.
• Buy the Diono Radian 3R if you are buying three seats at once and the budget is the binding constraint.
• Buy none of them if your back seat measures under about 51 in of usable width — the problem is the car, and the answer is seating position, not product choice. See where to install a car seat.

For the full field rather than this head-to-head, see best car seats for small cars, and how many car seats fit in my car for the measuring method.