Diono Monterey® 4DXT Booster

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The original monterey® booster has evolved!

Back in 2008, the original American expandable booster seat was created at Diono. Fast forward to today as we welcome the next evolution in a long-standing legacy. Diono has taken the award-winning Monterey and painstakingly engineered 15 upgrades to create the Monterey® 4DXT. From the remodeled headrest, enhanced fabric covering, contoured seat base and breathable exo-shell panels, every last detail was considered to create a contemporary new look.

Contoured to fit and shaped in harmony with your child, Monterey 4DXT adjusts and expands as your little one grows to offer wonderful all-round protection. The height and width can be adjusted independently for safety that envelopes their head and shoulders up to 12 years of age. A simple-touse dial on the back adjusts the width of the seat to fit a child’s shoulders up to 20” wide, while the headrest adjusts up to 6.4” height with one hand for an easy precise fit.

The remodeled headrest is lined with thick EPP foam for better child comfort and improved side impact performance. This is combined with deeper side wings and Diono 3-layer Side Impact Protection System built in. From the EPP foam coating, to the molded rigid shell casing and EPS coated outer shell, Diono lovingly engineered every detail to keep your little one safe, mile after mile.

 15 Improvements

  • Re-modeled headrest improves side impact performance
  • Optimized headrest shape improves head containment in the case of a collision
  • Thicker headrest EPP for better child comfort and sleep support
  • Deeper side wings improve side impact performance
  • Built in 3-layer protection system
    • Layer 1 - added EPP on inside for shock absorption
    • Layer 2 - molded rigid shell casing
    • Layer 3 – EPS material added to outer shell to absorb impact forces
  • Breathable exoshell side panels with enhanced airflow
  • Ergonomically contoured base
  • Improved child seating position
  • Luxury AIRTEK foam provides additional seat base cushioning
  • Refined seat back design, width reduced by for optimized vehicle fit but without a reduction in seat capacity
  • Better access to vehicle seat belt buckles for easy installation
  • Improved belt positioning across the child’s waist
  • Upgraded, automotive inspired fabrics
  • Improved cup holder integration
  • Fully covered backrest to protect vehicle interior


  • Fits children 40 lb to 120 lb and 38" to 63" in height
  • Reclining backrest adjusts perfectly to any vehicle seat
  • 11 headrest positions extends up to 6.4”
  • One hand headrest adjustment system
  • Energy absorbing foam lining overprotects in all the right ways
  • Unique, simple to use dial on the back that adjusts the width of the seat by 20"
  • Reinforced sidewalls soften any impacts
  • Integrated LATCH connectors and front adjusters provide a safe and secure installation
  • LATCH adjuster straps for the perfect fit
  • Extra seat depth helps prevent slipping for a safe, secure feel
  • Easily converts to backless booster
  • Lower Belt Guide in backless mode helps position shoulder belt for proper fit
  • Retractable dual cup holders are extra deep and angled to keep drinks upright
  • Super portable, lightweight, easy to store and packs flat
  • Soft, absorbent fabric with unique geometric design for a stylish and comfortable ride
  • Machine washable cover on cold on a gentle cycle


  • Dimensions: 34.5" H x 24.4" W x 17.9" D
  • Weight: 16.9 lb.
  • Expiry date 8 years from date of purchase


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