The Peg Viaggio Flex 120 Highback Booster** is one of those boosters that fills a need and does it uniquely. It’s been on the market for many years and offers features for big kids that parents and caregivers appreciate.

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WEIGHT, HEIGHT, & AGE LIMITS:

Highback: 40-120 lbs.; 39-63”

Age: At least 4 years old

FLEX 120 OVERVIEW:

4D Total Adjust Technology: headrest, backrest, side panels, and recline adjust independently
Kinetic Pods for side impact protection
Rigid lower LATCH connectors
No armrests for easy buckling
5-position recline
Flame retardant free fabrics
Built-in cup holders
Folds for travel
MSRP $299.99

MEASUREMENTS:

Belt guide heights: 15 ½”-22 ½”
Inside shoulder width: 13-16”
Hip width: 14”
Seat depth: 11”
Seat weight: 16 lbs.

There are 7 fashions available.

FIT TO VEHICLE:

There are 2 main reasons you buy the Flex 120: it doesn’t have armrests so it’s easy to buckle, but it does have rigid LATCH connectors so it’s easy to install and stays securely in place. If the lower anchors in your vehicle are easy to reach, installation literally takes a second. If they aren’t, you’ll have to manipulate the upholstery in order to attach the connectors and it take more effort.

Because the Flex 120 is reinforced, Peg allows a gap behind the back of the booster. This is good news for those of us with vehicles that have head restraints that angle forward!

The rigid lower LATCH connectors are released by a handle at the front of the base and pop out from behind the seat. Red/green indicators on each connector show you if they are securely attached. Squeeze the handle again and push the base against the vehicle seat to hide the release buttons on each side of the base. This way the seat won’t accidentally be uninstalled.

Center LATCH installations with Non-Standard Spacing:

Permitted only in designated LATCH positions

Inflatable Seat Belts:

Peg defers to the vehicle owner’s manual. If the vehicle owner’s manual allows use with booster seats, they are allowed to be used with the Flex 120.

FIT TO CHILD:

Seat belt fit is very good for larger kids and check fit on smaller kiddos. What does that mean? In the pics below, look at the lap belt fit on the smaller child (C is 6 yrs old, 49 lbs., 46”) vs. the larger child (J is 8 yrs old, 80 lbs., 56”). The belt fit is better—lower on the hips, not so high on the belly—than it is on the smaller child but it is still a safe fit on C. Shoulder belt fit was good on both, crossing at the middle of the shoulder.

Maturity also needs to be considered with a booster without armrests. There is more freedom for a child to move around because the armrests aren’t there to nudge them back into position.

Adjustments to fit are made on the back of the seat. The headrest adjusts up separately from the torso wings. The torso wings widen to accommodate the child’s shoulders.

The base can also be reclined out away from the back of the vehicle seat, but there is already a nice amount of recline built-in to the seat.

COVER/MAINTENANCE/EASE OF USE:

Peg recommends following the washing instructions on the label of the fabrics. Mine recommended washing in the washing machine with cool water and hanging to dry.

Sometimes I mention the manual if it’s exceptional in any way (good or bad) and here’s my take on the Flex 120’s manual. Peg has always offered excellent manuals filled with valuable information and advice and this manual is no exception. While most booster manuals are short—some are double-sided pieces of paper—this one is a book coming in at 52 pages! But really, read some of it. Read the usage parts, of course, but read it because it covers a lot of basic child passenger safety.

FAA/LIFESPAN/CRASH GUIDELINES:

Because belt-positioning booster seats require the use of lap/shoulder belts, the Flex 120 cannot be used on an airplane.

The Flex 120 has a lifespan of 12 years. Peg follows NHTSA crash guidelines for replacement after a crash.

FLEX 120 ADVANTAGES:

Seat, headrest, backrest, and side panels adjust independently
Kinetic Pods for side impact protection
Rigid lower LATCH connectors
No armrests for easy buckling
5-position recline
Flame retardant free fabrics
Folds for travel
12-year lifespan

FLEX 120 DISADVANTAGES:

Booster can be too tall when adjusted for the tallest kids in vehicles with sloping rooflines
The Kinetic Pods must be manually unscrewed into position to provide full benefit. In a time where most side impact pods just . . . exist . . . I have a feeling Peg will evolve the design to be more user friendly in future iterations of the Flex 120 but for now, it’s twist, twist, twist. It’s a minor complaint in the end.

In a time where more and more vehicle manufacturers are placing seat belt buckles even with the vehicle seat because of improved crash performance, it makes buckling so much more difficult for booster-aged kids with limited dexterity. The Peg Viaggio Flex 120 solves the problem of not being able to see or easily reach the buckle by not having armrests and being narrow at its base, giving this age group the much-needed independence they and their caregivers want.

For additional information, please visit the Peg website: https://www.pegperego.com/flex120

Thank you to Peg for providing the Viaggio Flex 120 sample used in this review. All opinions and comments expressed are those of The Car Seat Pros.

2026 Peg Viaggio Flex 120 Highback Booster Review