In a nutshell

The first booster (group 2/3) seat to meet i-Size regulations, it has increased side impact protection, ISOFIX connection and shoulderbelt and lapbelt guiders for optimal belt positioning

What we tested

  • Ease of installing
    A star rating of 4.5 out of 5.
  • Comfort
    A star rating of 4.0 out of 5.
  • Safety features
    A star rating of 5.0 out of 5.
  • Style
    A star rating of 4.0 out of 5.
  • Durability
    A star rating of 4.0 out of 5.
  • Worth the money
    A star rating of 4.0 out of 5.
Overall Rating
A star rating of 4.3 out of 5.


  • Exceeds latest i-Size regulations, added seat belt cushioning and lap belt guide, lightweight, adjustable headrest, easy to install


  • Price might put some people off

Key features of the BeSafe iZi Flex Fix high-back booster

  • Age suitability: approx 4-12 years (100-150cm)
  • Weight: 4kg
  • Design details: Integrated carry handle, integrated side impact protection, additional SIP bumper, diagonal seat belt cushion, clip to help position lap belt. Adjustable headrest, slimline design, with detachable side protection to make more room in car
  • RRP: £249 (for the black; more for other colours)

The BeSafe iZi Flex Fix is a new high-backed booster seat for kids between 100-150cm, or 15-36kg (4 to 12 years), and according to the brand is the first in this Group 2/3 class to have been tested to the new i-Size regulation standards.

It is the first forward-facing seat we tried when our 5-year-old grew out of her extended rear-facing Axkid (she is very tall for her age, otherwise we would have kept her in that even longer), so we were a bit nervous testing it – it felt strange strapping her in with the seat belt for the first time, albeit within the guides of a car seat.

There is a huge variety of Group 2/3 high-back boosters out there. Many cost under £100, such as the Maxi-Cosi Rodi XP Fix or the Joie Trillo and Duallo models. However, you can also pay significantly more. The Cybex Solution will set you back just under £200, for example. The BeSafe’s iZi Flex Fix has an RRP of £249.

However, the brand promises quite a few design details and superior protection and safety (including being tested to the new standards), and a high-back booster will last you a number of years. So it is worth considering stretching your budget, if the details convince.

You can buy the BeSafe iZi Flex Fix from John Lewis, Uber Kids or Natural Baby Shower.

Your guide to booster seat laws

First impressions?

The iZi Flex Fix seemed very sleek and simple, but also good quality. I received the simple Black Mélange version, although more exciting colour-ways, such as Sunset Mélange (with red accents) and Sea Green Mélange are available, eight colour options in total.

A Group 2/3 car seat, what’s the best age child for this particular car seat and why?

The iZi Flex Fix is suitable for kids between 100 and 150cm, or approximately 4-12 years in age. It's a forward-facing seat only, so ideal for bigger children.

How does the BeSafe iZi Flex Fix install in the car, how easy is it?

The iZi Flex Fix has integrated Isofix connectors and can be used with or without these. It additionally is secured with the car’s seatbelt, which also holds the child in place.

It also has a feature that locks the Isofix connectors in extended position in case you struggle to find your Isofix anchor points and need to shove the connectors a bit vigorously in to connect.

The handle that releases the connectors locks into place (showing red) and prevents the connectors from sliding back into the seat.

I found this a bit confusing, and I needed to double check the instructions on how to use this correctly, but I imagine it can be useful.

In general, however, parents we surveyed* as well as customers of John Lewis and Natural Baby Shower found it easy to install.

Does it feel secure once in place?

The back and seat of the iZi Flex Fix aren’t fixed at a rigid angle – presumably because it allows you to recline the seat to suit your child. So it felt a bit ‘loose’ once in place, with quite a bit of give. However, once my 5-year-old was strapped in, it felt pretty secure, and the added benefit of the Isofix connection gives you extra reassurance.

How is strapping your child/ren in? How easy are the seat belt guides to use?

In common with parents we surveyed, who all gave the seat 10/10 for strapping your child in, I found it very easy to strap in my daughter, similar to other high-backed boosters. The seat has clear guides, and the diagonal strap is held in place very well, as you need to open and fasten the guide to thread the belt through.

The seat also features a lap clip that helps keep the lap belt in the proper position, which I think is great when your child is still younger.

You also have an extra cushioning pad (PAD+) that goes high across your child’s chest for additional chin and chest protection. This is very easy to clip on, and once in place, you can easily slide it in the correct position – although make sure you read up on the correct positioning of this. And be careful that you don’t forget about it when you move the seat from car to car.

What do you think of the design?

I like the simple design. It is not very fussy or flashy, but ticks all the right boxes in functionality.

Does it feel sturdy?

The BeSafe Flex Fix feels quite light, but sturdy in all the right places. I do think high-backed boosters feel so much more lightweight than more rigid seats for smaller children, but it seems sturdy enough. I did note that the integrated carry handle (very useful!) felt a little flimsy for my liking.

How many positions does the headrest have?

The headrest can be gradually adjusted upward by turning a lever at the side of the seat, to accommodate children as they grow. At its highest it reaches 82cm, which is comparable to Joie’s Duallo I recently tested. The headrest also features an interesting V-shape design that supports the child’s head while also allowing them a bit more of a view too.

Are there different seat positions? Does it recline?

The iZi Flex Fix does have a recline function. You have to pinch two levers on both sides of the seat to ‘recline’ the backrest. However, the change in recline seemed minimal to me, and my daughter didn’t seem to notice either way.

How comfortable is it for your child – what did your children feedback?

My daughter felt comfortable in the iZi Flex Fit, although she generally complains about how upright her new booster seats need to be.

She did appreciate the seat belt pad though – it definitely made the diagonal belt more comfortable. I don't think she finds it quite as comfortable for sleeping as her previous seat, although she did fall asleep on occasion.

By contrast, parents we surveyed as well as customers of John Lewis and Natural Baby Shower gave the seat 10/10 for comfort.

Tell us about its safety features?

The BeSafe iZi Flex Fix is packed full of safety features, and the brand claims it is the first high-backed booster to conform with the new – more stringent – i-Size regulation. According to the manufacturer, the seat has three levels of side impact protection.

It has integrated side impact bumpers, plus additional SIP+ pads that you can clip onto the side of the seat, on the side of the door. These absorb additional force in the event of a side collision, acting a bit like a car’s crumple zone. The lapbelt guide is also a simple, yet effective safety feature as it ensures the belt is positioned optimally.

The seat’s safety was mentioned by Natural Baby Shower, John Lewis and Pramworld customers, with many choosing the seat for this reason.

What do you think of the size of the car seat?

The iZi Flex Fix is designed to be slimline and can be adapted to fit more seats or people in a car – something much appreciated by customers of Natural Baby Shower as it meant they could fit three seats in the back. The SIP+ bumpers can be used just on the door side, for example, and the integrated SIP bumpers can also be removed on the side facing the inside of the car for extra space. The dimensions of the seat are 42x52x64cm (in its lowest position and including its integrated SIP bumpers). Its width without the SIP bumpers is 44cm.

Will your children fit in it until they are 12 years old (36kg), do you think?

The BeSafe iZi Flex Fix does seem quite slimline, but equally it’s not too restrictive with the innovative headrest. It also doesn’t have any ‘horns’ or armrest (as the brand reckons these often lead to the wrong installation), so I do think it will accommodate a growing child really well.

Is it easy to clean?

There are no specific instructions on how to remove the seat fabric, just a tip to take care to remember how you did it, so that you can put it back on properly. However, the fabric is quite easy to spot clean in between, and doesn't mark badly. In our survey, 66% of parents were also happy with how easy the seat is to keep clean.

How heavy is it?

At 4kg I thought the iZi Flex was very reasonable. It’s super easy to swap between cars or take along on your travels – in our survey, 66% of parents gave the seat a score of 8/10 or more for how easy it is to transfer between cars. It also has a built-in handle to make carrying it about even easier.

What design feature do you like most in the car seat?

I like the extra padding around the diagonal seat belt and the clip that keeps the lap belt in place. I appreciate that they help keep the seat securely fitted to your child.

What’s in the box?

  • Car seat
  • Extra side impact panel
  • Cushioning pad for seat belt
  • Instructions

How easy was the iZi Flex Fix i-Size to assemble? Were the instructions useful?

The seat was very easy to assemble – it’s quite self-explanatory. However, I did refer to the instructions for correct positioning of the seatbelt padding.

Are there any accessories needed or available?

Make sure you always have the padding for the diagonal seat belt and the SIP+ with you, if you move the car seat. These are vital accessories to get the most safety benefit out of your iZi Flex Fit.

Who is this car seat best for?

This is a fantastic seat to ease the transition from toddler car seat to high-backed booster. The extra safety features provide huge peace of mind, and help with positioning your little one.

What do you wish you had known before you got it?

It is always useful to do your safety research when it comes to buying car seats. It’s really useful to know BeSafe’s background as a brand and the amount of research they put into their seats’ safety credentials.

Is the BeSafe iZi Flex Fix value for money?

I don’t agree with those that reckon ‘you get what you pay for’ when it comes to car seats, as some cheaper models do have some great security features, and all car seats need to meet certain standards. However, the BeSafe iZi Flex i-size car seat does offer a number of interesting design features, with extra security built in. It is also developed by a pioneering brand, so I feel we are in particularly good hands with the iZi Flex. The RRP of £249 is quite high – you can get a high-backed booster for much less – a point that a Natural Baby Shower customer mentioned, before adding that the seat’s safety was their reason for buying the seat in spite of the price. When you consider how long this car seat will last us – potentially another 7 years – it does seem worth the expense.

Would you recommend this car seat?

I would definitely recommend this car seat, especially for those with more than two kids. It is very versatile, lightweight and adjustable, but is packed full of safety features that will do their best to keep your growing child safe. What’s more, all the parents we surveyed gave the seat an overall rating of 9/10 or 10/10 and said they would buy it again.

*MFM survey December 2019 of 564 users

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Product Specifications

ModeliZi Flex Fix i-Size
Suitable for
Child age (approx)4 years to 12 years
Child Height100cm to 150cm
Dimensions & Weight
Car seat installationIsofix base
Removeable cover for washingYes
Side crash protectionYes
Recline positions2
Height adjustible headrestYes