The Britax One4Life Slim ClickTight All-in-One car seat has a mile-long list of features: a robust ClickTight belt-tensioning lockoff panel, a top harness slot height higher than most harness-to-booster seats, a top shoulder belt guide higher than most dedicated belt-positioning booster seats, flame retardant-free machine washable fabrics, and more! What else could we talk about in our review? Plenty.

Slim and ultra-narrow car seats are a hot trend right now. And while this new trend has been a godsend for many parents and caregivers looking to squeeze 3-across in their vehicle, it’s quite possible that the looming side-impact standard (FMVSS 213a), which will take effect on June 30, 2025, will force the discontinuation of some narrow harnessed car seats that aren’t able to comply with the stringent new requirements.