Diono does not sell this seat on Amazon. See its own site for photos.

Diono Monterey 6XT SafePlus High-Back Booster

A high-back booster seat with one mode: high-back booster 40 to 120 lb, 38 to 63 in.

At a glance

Fits children from 40 to 120 lb
Up to 63 in tall
High-back booster only
8-year usable life

Not sold on Amazon

Diono lists this seat on its US site. Buy from Diono or an authorized retailer, and confirm the exact model number before you buy.

Diono product page Manual

Specifications checked against Diono’s US site and manual on September 17, 2026. Not hands-on tested. How I research

Who is the Monterey 6XT SafePlus High-Back Booster for?

The Diono Monterey 6XT SafePlus is a folding high-back booster for children 40 to 120 lb and 38 to 63 inches tall. It restrains the child with the vehicle lap and shoulder belt, can attach to the lower anchors with adjustable LATCH straps, does not convert to backless, and expires 8 years after purchase.

Reasons to consider it

Adjustable LATCH straps that keep the booster in place, recommended by Diono when the car has lower anchors
A head support and side wing adjuster to set the shoulder belt guide at least 1 cm above the shoulders
A folding lever that clicks to lock the seat open or closed
A 120 lb and 63 inch upper limit with an 8 year life

Things to weigh up

No side impact pod or carry straps; those come only with the 6DXT
Not usable with lap-only, dual retractor, inflatable, motorized or door-mounted belts
Not certified for aircraft
Diono does not publish its width or weight on the support page

My take on the Monterey 6XT SafePlus High-Back Booster

The 6XT suits a family that wants a high-back booster that stays put with LATCH straps and folds for storage. The trade-off is that it never becomes a backless booster, and Diono does not publish its width or weight on its support page. It shares a manual and limits with the 6DXT SafePlus, but the 6DXT adds a Side Impact Management Pod and backpack carry straps.

A research summary of Diono’s published specifications and manual, read October 7, 2026. Not a hands-on test or a crash-safety rating.

Who the Monterey 6XT SafePlus High-Back Booster fits

This seat covers one stage. Diono gives it a 8-year life from the date of manufacture, so check the date label before using a hand-me-down.

High-back booster40 to 120 lb · 38 to 63 in: The seat’s own back and belt guide route the vehicle belt across the shoulder, and the sides give the child something to lean on when they sleep.

A school-age child with a backpack beside an empty high-back booster

What are the Monterey 6XT SafePlus High-Back Booster weight, height and age limits?

Diono Monterey 6XT SafePlus High-Back Booster limits by mode
Mode	Child weight	Child height	Minimum age	Conditions
High-back booster	40 to 120 lb	38 to 63 in	Not published	—

A child must meet every limit for the mode they use. The labels on your seat and its manual are the final word.

Monterey 6XT SafePlus High-Back Booster specifications

Seat weight: Not published
Width: Not published
Usable life: 8 years
Aircraft use: Not certified for aircraft

How the Monterey 6XT SafePlus High-Back Booster installs

Lower anchors: LATCH/UAS connectors. Check your vehicle manual for which seating positions have anchors, and switch to the seat belt once the child passes the anchor weight limit in the manual.

Every install is a fit between one seat and one vehicle. Read both manuals, and use a free inspection station if anything is unclear.

An empty car seat installed on a back seat, seen through an open car door

Will it fit your car?

Diono does not publish a width for this seat, so measure your back seat and compare it with the seat in a store before buying.

Check your vehicle manual for lower anchor positions and any head-restraint rules.
Rear-facing seats need front-seat room: try the install behind the driver before you commit.
Not certified for aircraft use: plan on gate-checking it or using a different seat to fly.

What features does the Monterey 6XT SafePlus High-Back Booster have?

LATCH/UAS connectors

What to know before you live with it

LATCH strap installation

You squeeze the folding lever and push the seat open until it clicks. Then you lay it on its side, press the silver cam lock and pull out both LATCH connectors without overextending the straps. Attach the far connector first, with the hook openings facing up, then push the booster back while pulling one adjuster strap tight and then the other. The seat bottom must sit flat, and a gap behind is acceptable as long as the head support touches the vehicle seat back or headrest. Without LATCH, the empty booster must still be belted in.

Source: Diono Monterey 6XT SafePlus manual (PDF)

Fitting the belt on the child

You press the head support and side wing adjuster and move it until the shoulder belt guide is at least 1 cm above the child's shoulders. After threading the shoulder belt through the guide, the manual asks you to pull some webbing out and let it feed back slowly, every time, and never to lock the retractor. A switchable retractor stays in ELR mode. The lap belt goes through both lap belt guides, flat across the hips, not high over the belly. The buckle should line up with the grey belt path guides; if it is pulled into the seat, use another seating position.

Source: Diono Monterey 6XT SafePlus manual (PDF)

Cover removal and washing

The head support cover comes off with the head support raised to its highest position, pulling the plastic flaps out of the side wings. The main cover comes off after you free the elastic strip around the manual storage area, the fabric around the cup holder slots, the elastic bands and hook and loop inside the folded seat, and the flaps under the lower belt guides. Remove the memory foam and do not wash it. The cover is machine washed separately in cold water on a gentle cycle, or hand washed, then dried flat away from direct sunlight.

Source: Diono Monterey 6XT SafePlus manual (PDF)

Is the Monterey 6XT SafePlus High-Back Booster recalled?

No campaign in the current NHTSA child-restraint data names this model family, and I have not run a separate review for it. Check your seat’s model number and date of manufacture before use.

NHTSA recall search · Recent car seat recalls

Monterey 6XT SafePlus High-Back Booster: common questions

What is the difference between the Monterey 6XT and 6DXT SafePlus?

Diono's box list gives the 6XT the booster, manual, registration card and a cup holder, and the 6DXT two cup holders, a Side Impact Management Pod and backpack carry straps. Another Diono answer says both come with two cup holders. Both share the same manual and the 40 to 120 lb, 38 to 63 inch limits.

Diono support: Monterey 6XT and 6DXT SafePlus (opens in a new tab)

Can the Monterey 6XT SafePlus be used without LATCH?

Yes. Diono recommends the lower anchors if your car has them, but the booster can be used with the vehicle seat belt alone, and it must stay belted in even when nobody is sitting in it.

Diono support: Monterey 6XT and 6DXT SafePlus (opens in a new tab)

Does the Monterey 6XT turn into a backless booster?

No. Diono says the 6XT and 6DXT do not convert to a backless booster and points to the Monterey 4DXT, Monterey 2XT, Cambria 2 and Cambria 2XT for that.

Diono support: Monterey 6XT and 6DXT SafePlus (opens in a new tab)

Can I use the Monterey 6XT on a plane or with inflatable seat belts?

Neither. The manual says it is not certified for aircraft because plane seats have no shoulder belt, and it lists inflatable seat belts among the belt types that cannot be used.

Diono Monterey 6XT SafePlus manual (PDF) (opens in a new tab)

When does the Monterey 6XT SafePlus expire?

Diono gives its boosters a life of 8 years from the date of purchase. If the purchase date cannot be determined, Diono uses the date of manufacture.

Diono support: Monterey 6XT and 6DXT SafePlus (opens in a new tab)

Answers refer to the model and manual version on this page. Check the instructions supplied with your seat.

Before you buy

Weigh and measure your child. The limits above are the manufacturer’s, and a child has to meet all of them for the mode they will use.
Confirm the exact version. Colors, retail exclusives and model numbers change limits more often than you would expect.
Read the manual before you buy, not after. It is linked above and holds the fit rules, the install methods and the expiry.
Check recalls by model number and date of manufacture, and register the seat with Diono so you hear about the next one.

Sources

Other Diono booster seats

Model	Top child weight	Seat weight	Width	Usable life
Monterey 6XT SafePlus High-Back Booster (this seat)	120 lb	—	—	8 years
Connect3 R 2-in-1 High-Back Booster	120 lb	—	—	8 years
Connect3 R Backless Booster	120 lb	—	—	8 years
Connect3 RXT 2-in-1 High-Back Booster	120 lb	—	—	8 years
Connect3 RXT Backless Booster	120 lb	—	—	8 years
Cambria 2 2-in-1 High-Back Booster	120 lb	—	—	8 years
Cambria 2XT 2-in-1 High-Back Booster	120 lb	—	—	8 years
Everett NXT High-Back Booster	120 lb	—	—	8 years
Monterey 2XT 2-in-1 High-Back Booster	120 lb	—	—	8 years
Monterey 4DXT 2-in-1 High-Back Booster	120 lb	—	—	8 years
Monterey 5iST FixSafe High-Back Booster	120 lb	—	—	8 years
Monterey 6DXT SafePlus High-Back Booster	120 lb	—	—	8 years
Solana Backless Booster	120 lb	—	—	8 years
Solana 2 Backless Booster	120 lb	—	—	8 years