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Britax Kidfix III M Cosmos Black

Britax Kidfix III M Cosmos Black

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Britax Kidfix III M Cosmos Black Britax Kidfix III M Cosmos Black Britax Kidfix III M Cosmos Black Britax Kidfix III M Cosmos Black

Britax Kidfix III M Cosmos Black

Cosmos Black
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available for immediate dispatch
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item features:
  • group 2/3, suitable from 4-12 years (15-36kg)
  • XP-PAD reduces frontal impact
  • Superior Side Impact Protection (SICT)
  • ergonomically optimised seat
  • ISOFIX or 3-point seat belt installation
Full product information >

Britax Kidfix III M Highback Booster

The Kidfix III M in Cosmos Black is the latest addition to the hugely popular Kidfix Range from Britax that's suitable for children from approximately 3.5 (15 kg) right the way through to 12 years of age (36 kg), and features a 20% larger seat to accommodate kids of all shapes,sizes and lengths. 



Safety plays a huge role in Britax's core values, so each and every seat that they release is brimming with state of the art safety features designed to provide you with complete peace of mind on every journey. The Kidfix III M features SICT (Side Impact Cushion Technology) as standard to provide an extra barrier between your child and the car's exterior. To utilise the SICT feature, simple twist the SICT out from the backrest of the seat on the side closest to the door and you're good to go, the Side Impact Cushioning will absorb energy and force on impact, minimising the amount of force that reaches your child in the event of a side-on collision. 


In addition to SICT, the Kidfix III M is fitted with SecureGuard, a feature that provides an extra point of contact between your child and your vehicle's 3-point seat belt. SecureGuard holds the lap belt in the optimum position across your child's pelvis, reducing the amount of abdominal force by up to 35%* in the event of a front-on collision.

*Observed during internal Britax Romer crash tests using Q6 dummy, equivalent of an average 6 year old child. 


Additional protection comes from the shell of the highback booster, with the height providing complete protection from head to hip which is particularly important in the event of a side-impact collision, while the padded headrest keeps your child's head and neck well supported. 



The Kidfix III M is ergonomically designed to provide your child with unbeatable comfort, a feature that is particularly important for a seat that will see your little one through multiple growth spurts. The 20% larger seat also comes with an improved shape and extra padding to ensure total comfort on even the longest journeys. The super easy, adjustable headrest can be re-positioned even when your child is strapped in, and is designed to help support their head if they fall asleep. The headrest even comes with indicators to show the correct position for your ever-growing child - optimum positioning is just above the shoulders. 


The backrest of the Kidfix III M is V-shaped, providing plenty of room for your child's back and shoulders to rest comfortably and well supported against the backrest. The backrest is also adjustable to suit the seats in your vehicle, ensuring your Kidfix III M sits flush against the seat back. This ensures the most comfortable and natural positioning for your child. 


Finally, the easy to remove, machine washable cover allows you to keep the car seat clean and fresh in the event of spills or accidents, simply pop it off and put it in the machine, then slip it back on when it's clean. 


The Britax III M is a great all-round highback booster, featuring plenty of longevity and packed full of safety features, it's the only seat you'll ever need for your toddler. 



  • group 2/3, suitable from 4-12 years (15-36kg)
  • XP-PAD reduces frontal impact
  • Superior Side Impact Protection (SICT)
  • ergonomically optimised seat
  • ISOFIX or 3-point seat belt installation
  • adjustable V-Shaped backrest grows with your child
  • height adjustable ergonomically designed headrest
  • intuitively positioned seat belt guides over shoulders & pelvis
  • removable, padded cover

Suitability: Suitable from 4-12 years (15-36kg)


Group: 2/3


Installation: Forward Facing, ISOFIX/3-point seat belt



Height: 67-85cm

Width: 54cm

Depth: 43cm


Weight: 7.5kg 

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We aim to dispatch all 'available for immediate dispatch' orders placed by 12pm the same working day.  Exceptions include made to order items for example some nursery furniture or direct ship items sent by the manufacturer directly to the customer.  In these cases an approximate delivery schedule is shown next to the product.


Our standard delivery cost is £4.99 for orders under £49.99.  Orders over £49.99 is free of charge.  Exceptions apply please view our Delivery & Dispatch page for details.
Any items 'available for immediate dispatch' will have the choice of standard delivery (2-3 working days) or express delivery (1-2 working days) this can be selected during the checkout process.
Orders for delivery to Scottish Highlands, UK Islands & Northern Ireland charged seperately. These schedules would exclude made to order and direct ship items.  For more information please click here


We offer a 14 day return policy allowing you to decide if the goods are as expected.  During this time you may return the goods at your expense or request collection with our courier company at a cost of £18 per parcel.  If the item has been used you will be unable to return the item under distance selling regulations.
Any damage in transit of shortages must be reported with 48 hours of receipt of the goods after this time claims will not be accepted.
Nursery furniture may incur additional charges for return.  Assembling furniture constitutes acceptance of the goods.  

For more detailed information please read our terms and conditions.

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Britax Kidfix III M Cosmos Black
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