| Child Fit Information | |
|---|---|
| Rear-facing Harnessed Weight | 5 - 50 lbs |
| Rear-facing Harnessed Height | Less than 49" |
| Forward-facing Harnessed Weight | 22 - 65 lbs |
| Forward-facing Harnessed Height | Less than 49" |
| Belt Positioning Booster Weight | 40 - 120 lbs |
| Belt Positioning Booster Height | 44 - 63" |
Pay in installments of $5.79 with
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Shipping Estimate
USA
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- USA
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Ships within 48 hours · Estimated delivery Aug 1 - Aug 6
Promo Codes Available:
For Your Every Summer RSVP, with Code: SUMMER15
Description
britax marathon g4 1 convertible car seat onyx Britax One4Life ClickTight All In One Car SeatOne4Life convertible to booster car seat grows with your child for 10 yearsfrom 5 120 lbs & up to 63 tall. As the only all in one with ClickTight, its easy to install in seconds, so youll know its right. Every time. Travel with peace of mind, knowing your child is surrounded in Trusted Britax Safety and Full Body Protection.. The new One4Life Premium ClickTight All in One (Ace Black) is dressed in a chic black knit fabric with luxe camel colored vegan
One4Life convertible to booster car seat grows with your child for 10 years—from 5-120 lbs & up to 63” tall. As the only all-in-one with ClickTight, it’s easy to install in seconds, so you’ll know it’s right. Every time. Travel with peace of mind, knowing your child is surrounded in Trusted Britax Safety and Full Body Protection..
The new One4Life Premium ClickTight All-in-One (Ace Black) is dressed in a chic black knit fabric with luxe camel-colored vegan leather accents. It offers effortless maintenance with lasting mess-proof protection thanks to the exclusive combination of StayClean: stain, moisture, and odor resistant technology + SafeWash: washer/dryer friendly, naturally flame retardant with no added chemicals.
Allow for 2 week shipping time.
Features you will love:
Converts from a rear-facing infant seat (5- 50lb) to a forward-facing 5-point harness seat (22-65 lbs) to a high-back belt-positioning booster seat (40- 120lb).
10 years of use: grows with your child from 5 – 120 lbs.
ClickTight Installation. Install with confidence, every time. You’ll know it’s right in just 3 easy steps: Pinch to open. Thread & buckle. Click it closed.
15-Position, Quick-Adjust Headrest & Harness create the proper fit as your child grows.
Patented V-Shaped Tether with staged-release stitches helps slow and reduce forward movement during a crash.
High Strength Steel Frame reinforces the seat structure to help keep it sturdy and stabilized.
Quick-Push, 9-Position Recline helps you find the most comfortable fit for your child and the best fit for your vehicle.
SafeCell Technology acts as a crumple zone, absorbing crash energy to help keep it away from your child.
Easy-Read Level Indicators help you find the correct recline angle when installing the car seat.
2 Layers of Side Impact Protection: Energy-absorbing shell and foam-lined surround your child’s head, neck & torso.
Stay-Put, Soft Comfort Pads help prevent the harness from rubbing against your child’s delicate neck.
Flip-Forward Buckle Pad stays out of the way for easy boarding; made with extra padding for premium comfort.
Built-In Cooling Channels & Ventilated Mesh improve air flow to keep your child comfortable.
Color-Coded Belt Guides make it easy to route the seat belt through the correct paths for rear-facing, forward-facing, and booster mode.
Removable Cover for easy cleaning without taking off the harness.
Harness Compartment neatly stores straps and buckles within the seat while in booster mode.
Dishwasher-Safe Cupholders easily twist out for cleaning between rides.
Removable Infant Insert helps keep your tiny baby safe and comfortable under 20 lbs.
Removable Head Pillow provides additional comfort for your growing baby.
Easy-Pull Harness Adjuster lets you tighten the harness using just one hand.
Harness Holder Slots keep the harness straps out of the way while your child gets in and out of the seat.
Tether Storage keeps the tether straps organized and out of the way when not in use.
Built-In Arm Rests keep your child happy and comfortable while they ride.
5-Point Safety Harness with diamond weave webbing.
Tag-Free Headrest supports your child’s head and neck without irritation.
Product Size
| Exterior Product Dimensions | |
|---|---|
| Product Weight | 30 lbs |
| Product Dimensions (L x W x H) | 20.5" (L) x 19.5" (W) x 25" (H) |
| Headrest Fully Extended Height | 33.5" |
| Fully Reclined Depth | 30" |
| Fully Reclined and Headrest Fully Extended Depth | 35.5" |
| Interior Product Dimensions | |
|---|---|
| Seating Area Depth | 13.25" |
| Seating Area Width | 11" |
| Shoulder Width | 14" |
| Harness Slot Heights | 15 positions, 9" - 19" |
| Buckle Strap Positions | 5.5" / 6.75" / 8.75" |
| Recommendation |
|---|
| Britax strongly recommends that children should be secured with a harness system until they exceed the weight or height limits specified. |
Care
Read how to care for your car seat here
Warranty
Limited 1 year warranty information can be found here. 10 year expiration.
Video
Product Origin: Proudly designed, tested and built in the USA with US and global components for safety and quality.
About Britax
At Britax, we believe family life should be lived without limit. A world where parents and children are free to make the most of every moment together. And we think it's our responsibility to make this happen. By driving safety standards to ensure children have never been better protected on the move. By pushing boundaries in smart design to make life in motion run smoothly. By extending a helping hand – or two – and always celebrating the journey.
We've been leading the way in child safety technology for more than 70 years. Always innovating, always focusing on what's best for the child, always going beyond 'good enough'. From Europe's best-selling car seat brand, we've become one of the brands most trusted by American families since we launched here in 1996.
Since then, we've revolutionized side impact protection, transformed safe seat installation, and introduced a range of smart strollers designed around the changing needs of today's families.
Our ongoing, open-ended conversation with parents is complemented by our work with car manufacturers, government bodies, and child passenger safety experts – collaborating, advising and using our industry-leading testing facilities to continually find ways to give parents the products and the reassurance to live family life without limit.
Because we believe in helping every parent and every child find their family freedom.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.2 ★★★★★
Based on 19 reviews
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Product Reviews
★★★★★ 5
Good shorts but they run big
Size: 38, Color: Dusty Olive
I've been losing weight and picked these up in my new size (38). It turns out these are cut for a generous American midsection, and have an elastic fit in the waist, so you can (and probably should!) safely go down a size. I got mine in 34 instead and they fit great.
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Reviewed in the United States on May 22, 2026
★★★★★ 5
Great fit, functional, most comfortable shorts!
Size: 30, Color: Anthracite Camo
These are my go-to shorts, I now have five pair in different camo colors! I suggest one waist size smaller than you normally wear, (I buy a 30 instead of a 32, because they stretch and would be too sloppy if I purchased my regular size). The large open slotted pocket on the left, behind the Velcro flap pocket, is perfect for a normal sized cell phone. Plenty of utility pockets for EDC. Since these stretch slightly to accommodate movement and sitting, they are extremely comfortable. Also, my wife says they are good looking on me, so that gets an extra star!
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Reviewed in the United States on March 24, 2026
★★★★★ 5
great shorts
Size: 38, Color: Gunmetal
excellent shorts. slightly loose around the waist, which i prefer. inseam is perfect just above the knee. light weight
and roomy. wash well.
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Reviewed in the United States on May 24, 2026
★★★★★ 5
The perfect throw-on athletic dress (with built-in shorts!)
Size: Small, Color: Navy Blue
I’ve been loving this athletic dress—it’s one of those pieces that’s both functional and cute, which is hard to find. The fabric is lightweight, breathable, and slightly stretchy, so it’s comfortable whether you’re running errands, going for a walk, or just chasing kids around all day.
The built-in shorts are a huge plus. They stay in place well and make it feel more secure than a regular dress, especially on busy days. I also appreciate the pockets—they’re actually usable and don’t feel bulky.
The fit is relaxed and flowy, which I personally like because it’s easy and flattering without clinging. The straps are adjustable, so you can customize the fit a bit depending on your height or preference.
I’d say it runs true to size for a looser fit. If you want it more fitted, you could size down, but I like the casual, sporty look as is.
Overall, this is a great everyday summer staple—super easy to style with sneakers or sandals, and perfect for travel or on-the-go days. I’ll definitely be getting more colors!
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Reviewed in the United States on April 24, 2026
★★★★★ 5
Perfect for summer days.
Size: Medium, Color: Deep Gray, Size: Medium, Color: Deep Gray
I absolutely love this little athletic summer dress. I typically wear a size ten and ordered this in a medium and it's a perfect fit. I have the straps short so way it doesn't look baggy. It is super soft and comfortable. It is breathable and a perfect cut and length for me so so I plan on wearing it all during hot summer days. This is very versatile and easy to style by layering different things underneath it. I have a gray and leopard sports bra that is a really close shade of gray so it almost looks like it's one piece. I plan to order the teal as I have a swimsuit top that will match that color spot on. It seems like it is good quality and should hold up well to normal usage. I like that it has really big pockets , but I likely will not use them often lol. I just like the fact that if I need to have pockets they are there.
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Reviewed in the United States on April 15, 2026