radian® 3RX

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Radian 3RX - Red

the original 3-across car seat

The Radian® 3 RX is lovingly engineered with a full steel frame and aluminum reinforced sides to maximize protection and has been designed to fit your lifestyle. The unique superlatch™ system makes installation quick and easy and the memory foam cushioning, padded harness and specifically angled cup holder help to keep your little one happy on life’s short or long journeys. Your little one will remain secure and comfortable with added support cushions and plenty of room to grow. We aim to keep your little one happy wherever life takes you. We’ve thought of everything so you don’t have to.

car seat installation

why parents love me

I use the Radian 3RX and we are so grateful that it is so narrow, as we have to fit 3 carseats in our vehicle! The material is soft and comfortable and because it is made of steel, it really puts me at ease and reminds me that they are safe in their diono.


product specs

product specs

5-45lbs / 2.3-20.5kg

22-65lbs / 10-29.5 kg

Booster mode
50-120 lbs / 22.7-45.4 kg

Seated torso height
8.25-17″ / 21-43.2 cm

Overall maximum height
up to 57″ / 144.8 cm

care & maintenance

Cover machine washable at 86F/30C/Cold

tips and tricks

installation tips

    • read the manual the comes with your car seat

    • read the vehicle manual

    • find a certified child passenger safety instructor or technician to help you and check your installations
  • airline use

    • unfold the Diono car seat before boarding the plane and ask the flight attendant for seatbelt extenders

    • make sure to install the car seat next to the window so passengers can get by in case of an emergency

    • make sure to take the slack out of the seatbelt extender before connecting to the airplane seatbelt
  • rear-facing installation

    • first secure the detachable base and slide in the locking mechanism

    • adjust the harness to be the proper height for rear facing

    • adjust the head support to fit your child properly
  • folding & unfolding

    • to unfold: lay the car seat down on a stable flat surface and undo the velcro strap, tuck it in behind the fabric and open seat until clicked and locked.

    • to fold: remove the red velcro strap from behind the fabric and loosen up the harness as much as possible so they are at the top of the car seat. release the lever at the bottom of the car seat and push seat inward - secure the top with the red velcro strap.
  • right for newborn?

    • whether you buy an infant only car seat or an all-in-one convertible car seat, both car seats have to meet the same standard

    • seats like the Diono all-in-one convertible car seats come with an infant cushion insert to properly fit your child in the harness

    • all-in-one convertibles are more economical - they have a lot of room for growth for your growing child
  • award winning car seats

    baby on board!

    Keep the little ones comfortable and positioned well when on the move, and stay one step ahead with cleverly designed accessories.

    why parents chose me

    rear facing for longer

    Allows children to sit safely rear-facing from 5-45lbs / 2.3-18.1kg (44″/ 112cm in height)

    stylish and snug

    Modern, versatile cover in soft, premium fabric for a comfortable ride everyday – it’s absorbent, easy to remove and machine washable too!

    all aboard

    Low sitting profile makes it easy for your child to climb in and out of their seat as they grow.

    proper fit

    Secure the littlest bundles of joy in our premium head and body support – for their very first journey out in the world.

    three's not a crowd.

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    parents’ choice

    your choice

    colours that speak all languages

    parents love the radian® 3RX!

    “My family and I were traveling on vacation, and had an accident after being hit by a semi. Our vehicle did several spins, and rolled several times. My one year old son was seated behind the passenger’s seat, the side of impact. As we were rolling his window broke. Once we came to a complete stop, his seat had not moved. He had NO injuries. He was the only one in the car completely unharmed. The car was totalled. I’m convinced it’s because of the reinforced steel/aluminum frame. I’m forever grateful for how well made this carseat is. Thank God for the friends who purchased it as a shower gift. This carseat saved my baby’s life.”

    -Grateful Mom, Cincinnati, OH

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    can the radian 3RX fit 3-across in my car?

    Most likely, yes, as long as you have 51” (129.6cm) in the back row from vehicle armrest to armrest. It may be necessary to install all three using the vehicle seat belt system.

    can the infant head and body supports be used on the 3RX?

    Yes, they can be used including on all the Rainier and Radian line convertible car seats.

    are the harness pads and buckle pads required on my seat?

    Yes, they are required while your child is sitting in forward-facing. They are optional but recommended while sitting rear-facing. The center buckle pad is required at all times..

    what are the requirements to use the seat in booster mode?

    The child must weight at least 50lbs / 22.7kg and be at least 40″ / 102cm tall and shoulders reach the 4th harness slot.

    does a cup holder come with the car seat?

    Yes, a cup holder is included.