SKU: 31146519715
britax marathon convert to booster

britax marathon convert to booster Britax Poplar S Convertible Car Seat

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Description

britax marathon convert to booster Britax Poplar S Convertible Car SeatThe Britax Poplar S Convertible Car Seat is the best space saving convertible car seat for parents seeking advanced crash protection, ClickTight fast installation, and 3 across seating capability in a compact 17 inch profile. This convertible combines advanced safety innovation, superior comfort, and space saving design to make every ride safer and simpler. Built with ClickTight installation technology and ReboundReduce stability bar, this seat

The Britax Poplar® S Convertible Car Seat is the best space-saving convertible car seat for parents seeking advanced crash protection, ClickTight® fast installation, and 3-across seating capability in a compact 17-inch profile. This convertible combines advanced safety innovation, superior comfort, and space-saving design to make every ride safer and simpler. Built with ClickTight® installation technology and ReboundReduce™ stability bar, this seat ensures a secure fit with minimal movement, giving parents confidence with every drive. Designed for long-term use, the Poplar® S transitions seamlessly from rear-facing (up to 50 lbs) to forward-facing (up to 65 lbs) without complicated conversion steps. Compare the Britax Poplar S to the Graco Extend2Fit: both offer extended rear-facing and forward-facing capability with adjustable headrests, but the Poplar S features ClickTight installation (3-step, pinch-thread-click system vs. traditional LATCH), ReboundReduce™ stability bar, SafeCell® crumple technology, patented V-shaped tether with staged-release stitches, naturally flame-retardant SafeWash® fabrics, 14-position no-rethread harness, 6 recline positions, carbon steel frame, 17-inch slim profile for 3-across seating, and 50+ years of Britax heritage. Choose Poplar S if you want premium crash protection, fastest installation, and compact 3-across capability; choose Graco Extend2Fit if you prioritize budget-friendly pricing. Inside, your child enjoys premium comfort with refined inserts, plush padding, and 6 recline positions for a custom fit at every stage of growth.

Inside, your child enjoys premium comfort with refined inserts, plush padding, and 6 recline positions for a custom fit. SafeWash® fabrics, naturally flame-retardant and machine washable, make cleanups effortless while maintaining Britax's commitment to quality and safety. The ClickTight® installation system simplifies setup with just three steps—open, thread and buckle the seat belt, then click it closed—for confident installations every time without confusion or error. The ReboundReduce™ stability bar helps minimize movement in the event of a crash when rear-facing, providing additional protection during the most critical early years. SafeCell® Technology acts as a crumple zone to absorb crash energy and divert it away from your child. The patented V-shaped tether with staged-release stitches helps slow and reduce forward movement during impact. The 5-point safety harness distributes crash forces evenly across your child's body for maximum protection. The carbon steel frame reinforces seat structure for strength and stability across thousands of miles. The 14-position headrest and harness adjust easily as your child grows without rethreading, eliminating annual maintenance hassles. Three premium comfort inserts, including one specifically designed for infants up to 22 lbs, provide plush, tailored support from birth through toddlerhood. The SpaceSaver™ slim 17-inch profile fits 3-across in most vehicles while maintaining interior comfort—a critical consideration for multi-child families. Six recline positions offer optimal comfort and vehicle fit for both rear- and forward-facing modes. Automatically-tensioning harness ensures the restraint is always secure and snug. Clearly labeled belt paths make installation straightforward and error-free for any caregiver. Dual removable, dishwasher-safe cup holders keep drinks within reach while simplifying cleanup. The naturally flame-retardant SafeWash® fabric is durable and safe to machine wash and dry for quick cleanup after spills and accidents.

Britax Poplar® S Convertible Car Seat Features:

  • ReboundReduce™ stability bar: Helps minimize movement in the event of a crash when rear-facing, providing added protection during critical early years

  • ClickTight® installation system: Simple three-step system—open, thread and buckle, click it closed—for confident installs every time without LATCH confusion

  • SafeCell® technology: Acts as a crumple zone to absorb crash energy and divert it away from your child

  • Patented V-shaped tether: Staged-release stitches help slow and reduce forward movement during impact

  • 5-point safety harness: Distributes crash forces evenly for maximum protection across torso and shoulders

  • Carbon steel frame: Reinforces seat structure for strength and stability across extended use

  • Naturally flame-retardant fabrics: SafeWash® materials are free from added FR chemicals for safer comfort

  • SpaceSaver™ slim 17-inch profile: Fits 3-across in most vehicles while maintaining interior comfort for all passengers

  • Refined comfort inserts: Three premium inserts, including one for infants up to 22 lbs, provide plush, tailored support

  • 14-position headrest and harness: Easily adjusts as your child grows without rethreading—annual adjustments simplified

  • Six recline positions: Offers optimal comfort and vehicle fit for both rear-facing and forward-facing modes

  • Automatic tensioner: Ensures the harness is always secure and snug throughout wear

  • Clearly labeled belt paths: Make installation straightforward and error-free for any caregiver

  • Dual removable cup holders: Dishwasher-safe for easy cleaning and convenient drink storage

  • SafeWash® fabric: Durable, naturally flame-retardant, chemical-free material that's safe to machine wash and dry

  • Convertible rear-to-forward transition: Smoothly transitions from rear-facing (up to 50 lbs) to forward-facing (up to 65 lbs) without complicated steps

  • Compact, space-saving design: Ideal for smaller vehicles, multi-seat setups, and families needing 3-across capability

Safety and Protection Features:

  • ClickTight® three-step installation: Industry's fastest installation system reduces setup errors and ensures secure fit every time

  • ReboundReduce™ stability bar: Minimizes crash movement during rear-facing collisions

  • SafeCell® crumple technology: Absorbs and redirects crash energy away from your child

  • V-shaped tether with staged-release stitches: Reduces forward movement during impact crashes

  • Carbon steel reinforced frame: Maintains structural integrity during collisions

  • Energy-absorbing shell: Multiple layers protect head, neck, and torso

  • 5-point harness system: Distributes forces evenly across safety zones

  • Automatic tension harness: Stays secure without manual tightening

Comfort and Convenience:

  • Six recline positions: Custom fit for sleeping newborns to alert toddlers

  • 14-position no-rethread headrest: Grows with child from birth through age 5+ without annual rethreading

  • Three premium comfort inserts: Newborn insert supports infants up to 22 lbs with proper spinal alignment

  • SafeWash® naturally flame-retardant fabric: Machine-washable comfort without added chemicals

  • SpaceSaver™ 17-inch slim profile: Maximizes cabin space while providing full-size interior comfort

  • Dishwasher-safe cup holders: Easy cleanup keeps seat fresh

Why Choose Britax Poplar S?

The Poplar S delivers exceptional value for parents seeking a space-efficient convertible with premium crash protection and installation ease. The ClickTight® system is the fastest installation available—no threading LATCH straps, no confusion about proper tension, just three intuitive steps. The 17-inch slim profile is unmatched in the convertible category, enabling true 3-across seating in vehicles where traditional convertible seats won't fit side-by-side. Combined with 50+ years of Britax safety heritage, advanced protection technologies like ReboundReduce™ and SafeCell®, and naturally flame-retardant SafeWash® fabrics, the Poplar S makes premium safety accessible and practical for modern families.

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Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. 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
SKU: 31146519715

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Amazon Customer
Birmingham, US
★★★★★ 4
Make sure you size up!!
Size: 4X-Large, Color: B004
Allllllmost 5 stars if the sizing was correct. I’ve been on the hunt for a decent fitting pair of women’s boxer briefs. I would say these are more so boyshorts. That being said, I wanted something loose for sleeping in so I got TWO sizes up. I normally go for a 2x and got a 4x and they’re perfect fitting. So, you didn’t get what I was looking for but did end up with some decent fitting undies. So I can’t complain too much. Just not the boxer briefs I was hoping for. Super stretchy and soft. Comfortable for sleeping in.
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Reviewed in the United States on March 3, 2026
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Barbara Bowen
Battle Creek, US
★★★★★ 5
Really comfortable, good fit
Size: 6X-Large, Color: 5 Pack(black,black,blue,blue,light Coffee)
These are very lightweight and comfortable. The material stretches freely and doesn't bind up anywhere. If you go by the size guide, they should fit perfectly neither too loose nor too tight. Would definitely recommend.
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Reviewed in the United States on April 23, 2026
K
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Krypto Alley
Waukegan, US
★★★★★ 3
These don't work for me...
Size: Medium, Color: B005
First the good... I like the material; it's very soft, light, and stretchy. I also like the colors, but that's all I like about these boyshort panties. My main goal for panties is to have them NOT ride up into my butt crack leaving the bottoms of my butt hanging out. It's probably comfortable for some, but it drives me nuts to feel this constant need to pull them out of my butt crack and down over my butt cheeks. If I wanted my butt hanging out I'd buy thongs, LOL. The part I really don't understand, is why they make the front and the back the same width/length. I mean clearly more material would be needed in the back to fit around two round humps, right? I mean I guess unless you have what I call a pancake butt, I don't see why there shouldn't be more material on the backside of the underwear. Why is it so dang difficult to find underwear in this style to fit up over butt cheeks? If I pull them down enough to cover the bottoms of my cheeks then the waistband is sitting right at the top of my crack which is extremely annoying (then I feel this constant need to pull them up!) especially when the front is long enough to go up to my belly button!! Who are they making these underwear for??? Ladies with FLAT butts apparently. For reference, I'm 5'5" 130 lbs, hips 37", waist 27", athletic build, as in lean but with muscular glutes & quads from speed skating. Not only are they not made big enough to go up over my rump while still keeping my cheek bottoms from hanging out, but they're too long in the front cause they constantly roll up in the front. I've even tried turning them around, even though they seem to be exactly the same front to back, and they fit exactly the same, no surprise there. I may just be out of luck finding comfy boyshort panties that actually fit the way I want them to. :/
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Reviewed in the United States on December 15, 2025
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Dominique Davis
Cuba, US
★★★★★ 5
Super comfy!
Great colors, super comfy, soft and druable!!
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Reviewed in the United States on May 2, 2026
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JustAnotherShopper
Battle Creek, US
★★★★★ 5
Comfy and well made
Size: Large, Color: B2207sp
Love these! They stay in place, are soft and comfortable with just enough stretch but hold their shape. This is my 3rd order.
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Reviewed in the United States on February 21, 2026

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