Britax Advansafix M I-Size Car Seat Cosmos Black

The car seat is forward facing and is approved to the new i-size regulation, Will grow with your child ideal for every family thanks to the flip and grow function. You can switch from the integrated 5 point harness to the 3 point seat belt with just a few simple steps. In addition provides protection for all ages together with maximum flexibility.

7 - 10 Day Delivery
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Free Standard Delivery on Orders over £50.

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28 day, hassle free returns.

Family run business, established over 35 years.

I-Size safety for all ages

The safety of every child is very important to Britax and is approved to the new i-size regulation. Advansafix M i-size grows easily and comfortably with your child. Thanks to the flip and grow function, You can switch from the integrated harness to the car’s 3 point belt, the secure guard holds the lap belt in the optimal position over the pelvic bones, reducing the risk of abdominal injuries. Plus, the V shaped headrest provide protection in the event of a side impact

Key Features:

  • Suitable from 15 months to 12 years approx
  • Weight capacity up to 36kg max
  • 5 point harness 21kg max
  • Forward facing 76cm - 150cm
  • Fitting
  • Isofix and top tether 76cm - 102cm
  • Isofix and 3 point seat belt 100cm - 150cm or 3 point seat belt 100cm - 150cm

Easy recline

  • Easy recline is suitable for all ages and allows you to adjust the seat into comfortable forward recline positions, even when your child is in the seat and without having to re-adjust the top tether. Total convenience for both the parent and the child
V shaped headrest
  • Specially designed to control the movement of your child’s head, our V shaped headrest ensures optimal protection in the event of a side collision while providing ultimate comfort at the same time. Plus, the headrest and harness can easily be adjusted from the front of the seat to suit your child’s height
Soft neoprene performance chest pads
  • Soft neoprene performance chest pads fit comfortably on your child’s chest. They help reduce your child’s movement in the event of a collision, and add even greater comfort to the 5 point harness. Plus, they can be easily removed for washing without disturbing the harness
5 point harness 
  • We believe a 5 point harness is the safest way to secure your child in a car seat because it keeps your child safe and tight in the seat’s protective shell. In the event of a collision, the harness distributes the forces of the impact across 5 points, two at the shoulders, two at the hips and one where the harness buckles between the legs. This helps to protect your child from all directions of impact
Flip and grow
  • When your child reaches 15kg and up to a maximum of 21kg, you must change from the integrated 5 point harness to the car’s 3 point seat belt to secure your child in the seat. Thanks to the flip and grow function that’s now possible in a few simple steps. Simply adjust the headrest and stow the harness in the backrest so it won’t get lost. Then, switch the flip and grow adjustment plate so the secure guard is above the seat and you’re ready to go
Secure guard
  • The secure guard helps to protect your child’s delicate abdominal area by adding an extra 4th contact point to the 3 point seat belt. By keeping the lap belt in an optimal position over your child’s pelvic bones secure guard helps reduce abdominal forces in the event of a frontal collision by up to 35 %, and at the same time allows your child freedom of movement during the journey
Highback booster protection
  • The highback boosters protect your child in 3 ways: (1) The seat shell provides head to hip protection for your child, especially in the event of a side impact, (2) The upper and lower belt guides provide correct positioning of the seat belt, (3) The padded headrest provides safety and comfort for your child’s head and neck
Top tether
  • The top tether minimises the rotation of the car seat and this reduces possible injuries in the head and neck area in the event of a collision. Due to its twin anchorage points, the v shaped top tether offers even greater stability and security for your child than a seat with conventional tethers
Pivot link isofix system
  • In case of an impact, our patented Pivot link isofix system directs the force first downward (1), into the vehicle seat, and then forward (2), more gently greatly reducing the risk of head and neck injury for your child

More Information
Colour Cosmos Black
GTIN 4000985326245
MPN 2000034305
Age Suitability From 76cm to 150cm (15 months to 12 years approx.)
I-Size Yes
Weight 11kg
Open Dimensions H 60-83 x W 44 x D 47cm
Warranty 24 Months
Materials Quick remove machine washable cover
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Delivery  & Delivery Timescale:

We work with the UK’s leading couriers to offer quick and reliable service. All orders dispatched by our warehouse are sent on a next working day delivery. Never miss a delivery, with SMS and email time slots sent as standard with all orders.

Please check the product page for up-to-date delivery timescales (shown above the price); Items that show as ‘Stock Available’ are usually dispatched within one working day on a next working day delivery service. Items that are not available for immediate dispatch are clearly labelled with up-to-date delivery timescales.  We offer free standard next working day delivery on all orders over £50 to England, Wales, and parts of Scotland excluding the Highlands and Islands (i.e. zone 1). Please note that if multiple items are ordered with different delivery dates, all items will be dispatched together when in stock.

Certain products may be delivered Direct from the Brand using their own courier service. All products that use this service are clearly labelled on the product page with the expected delivery timescale.


For all deliveries the driver is not employed by Lesters Nursery World and although he/she will deliver your goods into your home, he/she may not deliver orders into a specified room. When you receive your goods, it is important that you inspect them before signing for the delivery. If you are suspicious that the goods are damaged, or the box containing the goods looks badly damaged, then you should sign for them as damaged or ask the courier to wait while you examine the goods. If the driver is unable to wait or the system does not allow you to sign the goods as damaged please take pictures in the presence of the driver. In this event, please contact us immediately so that we can resolve the situation with the courier. It is important that all original packaging is kept until you are satisfied with the goods and are sure that they will not need to be returned. Couriers will not accept goods if they are not packed securely.

Items sent with a courier will be delivered during working hours on Monday – Friday. We aim to dispatch items that are in stock within one working day, you will receive an email once we have dispatched the order informing you that the items are on their way. You will receive further communication from the courier (email and SMS) with live updates on the status of your delivery. If you have not received your items that are marked as available within 3 working days and had no communication from us or the courier please email or telephone us on 0161 720 7227..

Parcel delivery zones and supplemental charges are shown below. Delivery to zones 2 and 3 is usually on a 48-hour basis. The supplement for zones 2 and 3 is £8. This will be automatically added on the payment page.

Zone 1:England, Wales and parts of Scotland, excluding Highlands and Islands. The zone is made up of all postcodes not mentioned in zones 2 and 3.

Zone 2: The Highlands and Islands of Scotland - postcodes IV, HS, KA27-28, KW, PA20-49, PA60-78, PH17-26, PH30-44, PH49-50, ZE.

Zone 3: Northern Ireland, Isle of Man and Isles of Scilly - postcodes BT, IM, TR21-25.


Cancelling orders and Returns:

Buy with confidence with our hassle-free returns. You have the right to cancel any order made with Lesters Nursery World via our website, and a full refund will be given providing the items have not been dispatched. We recommend you send an e-mail to or call us immediately on 0161 720 7227 should you wish to cancel your order.

Any website order* can be cancelled in within 28  calendar days after receiving your order under the Distance Selling Regulations. All items must be unused, in their original packaging, and in a resellable condition. Postage costs involved in returning cancelled orders are at the expense of the consumer. This is generally up to £15 per box but can vary dependant on the size and weight of the item returned. This does not affect your statutory rights.

*Furniture that has been assembled by the customer or manufacturer may not be returned. Personalised items cannot be cancelled or returned once ordered.