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Description
britax relay Britax One4Life Slim All-in-One Car SeatThe One4Life Slim all in one car seat takes your child from birth to big kid with trusted Britax safety, ClickTight installation, and a slim SpaceSaver design. As a convertible and harness 2 booster seat in one, it grows with your child for 10 years. It starts rear facing with an extended capacity of up to 50 lbs., so your child can ride rear facing longer. It easily converts to forward facing toddler mode (up to 65 lbs.) and high back belt
The One4Life® Slim all-in-one car seat takes your child from birth to big kid with trusted Britax safety, ClickTight® installation, and a slim SpaceSaver™ design. As a convertible and harness-2-booster seat in one, it grows with your child for 10 years. It starts rear-facing with an extended capacity of up to 50 lbs., so your child can ride rear-facing longer. It easily converts to forward-facing toddler mode (up to 65 lbs.) and high-back belt-positioning booster mode (up to 120 lbs.) when your child is ready. With a slim outside and spacious inside, the 17.5” seat is designed to fit 3 across* without compromising safety and comfort. ClickTight helps you install with confidence, every time. The base and shell are easy to wipe down for hassle-free cleanup. The car seat cover is safe to machine wash and dry, and it’s naturally flame-retardant with no added FR chemicals. One4Life Slim features a high-strength steel frame, a SafeCell® crumple zone, and a V-shaped tether. As your child grows, you can easily adjust the 15-position no-rethread harness and headrest with one hand. With cooling channels, premium padding, three infant inserts, and built-in armrests, your child will love every ride.
- All-in-One Car Seat: One4Life® Slim is a convertible and harness-2-booster seat in one!
- It easily converts from a rear-facing infant and toddler seat (5-50 lbs.) to a forward-facing seat (30-65 lbs.) to a high-back booster seat (40-120 lbs.)
- 10 Years of Use: This slim all-in-one car seat grows with your child from 5 to 120 lbs. and up to 63” tall
- ClickTight® Installation: Install with confidence in 3 easy steps: pinch to open, thread and buckle, click it closed!
- SpaceSaver™ Design: Slim outside, spacious inside! The 17.5” seat is designed to fit 3 across without compromising on trusted Britax safety and premium comfort.
- Premium Fabrics: The woven mélange accents give the car seat cover a tailored look, while the soft knit fabric on the padding and inserts helps keep your child comfortable during every ride
- Woven Accents on the Exterior and Comfort Pads: Made from recycled polyester
- Hassle-Free Cleanup: Extra space between the shell and base means you can clean under the seat with ease – and with minimal grooves in the seating area and base, you can wipe it down with no fuss
- SafeWash® Fabrics: No more hand-washing or waiting for the cover to air-dry; just quick and easy cleanup so you can keep moving
- Naturally Flame-Retardant Cover: With no added FR chemicals
- Three Removable Infant Inserts: Help provide a better fit for infants 20 lbs. and under
- Accessible Color-Coded Belt Paths: Make it easy to route the seat belt through the correct path for each car seat mode
- Slide-Out Cup Holders: The dishwasher-safe cup holders slide out with ease for convenient cleaning and click back into place for a secure attachment during rides
\Cup-Holder-Free Option: Remove the cup holders completely and insert the armrest caps to save additional space - 15-Position No-Rethread Harness and Headrest: Adjust together quickly and easily with one hand to help create the proper fit as your child grows; no rethreading, ever!
- 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 with Easy-Read Indicators: Helps you find the most comfortable fit for your child and the correct angle for your vehicle
- SafeCell® Technology: Acts as a crumple zone, absorbing crash energy to help keep it away from your child
- Two Layers of Energy Management: The protective seat shell and foam-lined headrest help absorb impact energy and are designed to help keep your child's head, neck, and body safe
- Soft Comfort Pads: Help prevent the harness from rubbing against your child’s skin
- Flip-Forward Buckle Pad: Stays out of the way for easy boarding; made with extra padding for premium comfort
- Built-In Cooling Channels: Improve airflow to help keep your child comfortable
- Plush Padding: For superior comfort and a quiet ride
- 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
- 5-Point Safety Harness with Diamond Weave Webbing: Provides adjustment points at the hips, shoulders, and between the legs
- Tag-Free Headrest: Supports your child’s head and neck without irritation
*Britax cannot guarantee 3-across fitment in all vehicles.
Specifications
- Dimensions: 24.5"H x 18.5"D x 17.5"W
- Weight: 28 lbs.
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
4.4 ★★★★★
Based on 16 reviews
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Product Reviews
★★★★★ 3
Ehh
Size: Medium, Color: Multicoloured E-(5-pack)
Very thin, still comfy but very thin material. Super soft though. I've worn and washed and they have held up but I won't be repurchasing bc these are so thin
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Reviewed in the United States on April 14, 2026
★★★★★ 5
They’re fantastic!!!!
Size: X-Large, Color: Multicoloured E-(5-pack)
My clothing size is 16/18 and XL. Even though Amazon suggested a size XXL, I ordered my normal XL and they fit perfectly.
The fabric for this style is 92% bamboo viscose and is amazingly soft and almost silky feeling. I had ordered a different boy short in this brand but they were 80% bamboo viscose and the fabric was significantly heavier. I returned those and ordered these.
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Reviewed in the United States on April 25, 2026
★★★★★ 5
Boy have I bought A Lot of Underwear
Size: Medium, Color: Black,navy,melange,london Blue,burgandy
These are my favorite boyshorts so far. The little stripes kill me, they're so cute. I am now an expert on boyshorts. You should know, I always buy the color packs with boyshorts with a make-up that look like static on the tv. Not sure how else to describe that but they tend to be the same across the board and I think they're super cute, personally. The solid colors may be a different story. SO-Here's what I've learned: They're all basically the same, minus the material and how you like them to fit. You want to look at what the exact material content is. Do you like super soft, almost gauzy and you're not concerned with possibly snagging them? Then you'll want to find boyshorts with a high percentage of polyamide. These are not them. These are about 50/50 polyamide and polyester, which is firmer and has less stretch. Not gonna snag them in regualr situations. Still lots of stretch, though. Just more support and more excercisey material feel. But, there is enough polyamide in them to still feel soft. I prefer less plush and more support. There is a dash of spandex in there and that's good to accommodate many bodies and to hold their shape over time. I know some gals are looking for a softer, stretchier, plushy boyshort. They're easy to find. Look at the material listed. Okay, about sizing: These are stretchy. Not SUPER stretchy, like the gauzier underwear, but stretchy, and you'll fit in most of the sizes. The fit will just be different, obviously. I'm a large in regular pants typically. Size 12. Ten in a good month. I'm 48, 5'5 and 165 pounds. I've got a booty, but not super-duper bangin. Just big. Anyways, I've gotten my "true" size (L), sized up (XL) and sized down (M). Sizing up (XL) is too "poochy" feeling and just mildy wads up around where my legs meet my bits. Comfortable, and stay on but saggy feeling to me. The true-to-size, size large, are less "waddy" and fit fine! Loose enough to almost forget they're on. I've sized down to medium, and that's where my preference is. They fit like I have work out shorts on, just very short ones. More support but don't look ridiculous. I don't look like a sausage in them. Size small would be that on me-the sausage shorts. I mean, I'm wearing these around the house in the summer so I don't have to crank my A/C., and for bed. They aren't gonna be seen my many. Either way these are going to roll up (super skinny gals without thigh gap...do boyshorts roll up on you too? Always wondered that) but the smaller size on me seems to roll less, and that roll doesn't bother me. A roll is different from a "wad". Actually I wouldn't even call it a roll, I'd call it a "fold over". Ha ha I hope this helps and you understand my lingo. FYI I have found personally that most of these brands are the same exact thing from China, packaged and branded differently. The material is the big factor. But these are the only ones I've found with little pinstripes. CUUUTE. Good luck out there!
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Reviewed in the United States on June 17, 2025
★★★★★ 5
Great product
Size: Medium, Color: Black,navy,melange,london Blue,burgandy
I adore these! They're so comfy. When they first arrived they felt a little snug in the waist and leg holes, but I gently stretched them out before putting on and have had no problems since, even after washing/drying, i just put on delicates cycles. The slight snugness normally wouldn't bother me at all and most of my other undies are tighter, but I had surgery for endometriosis back several months ago so I need/needed something comfortable. I'm used to wearing hip huggers or bikini briefs.
I was concerned that boyshorts would ride up or that the legs would roll-which they do roll up slightly, but it's easy enough to adjust when putting on clothing and then I have no issues!-Once I tried these, they've become my favorite underwear. They're very soft and "seamless" and I like the fact they have no elastic. I have pain down my inner thighs that makes seams or elastic leg holes uncomfortable, but these undies are long enough and soft enough to provide coverage/protection in that area when wearing pants or leggings with inner seams, and makes it so much better to deal with.
I just ordered another package and I'm excited to have more pairs to replace my old undies with! Really happy with this purchase.
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Reviewed in the United States on March 11, 2022
★★★★★ 4
A Bit Too Smooth
Speaking as a petite person, these following boyshort underwear passed so many comfort levels down from the fit, stretch, fabric feel, and describe shape of the material. When it comes to undergarments and living in a hot desert, breathable clothing is a necessity. It maybe "just underwear", but they are very complementing on the body and invisible in your movement.
The crutch however, while the soft fabric maybe great with skin-contact - results with little grabbable or stickable surface for pads or panty liners that I own. Not having tried alternate pad or liner brands, I can't give a thorough idea of "Does it stick?" when it comes to this underwear. It's not to say it is completely unstickable, it'll will stick, but you really need to press in place. Major movement will crunch the pad/liner and you'll have to replace later in your day because you will feel it amiss.
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Reviewed in the United States on July 21, 2022