Protection That Grows
Suitable from 4 lbs. up to 120 lbs
Rear-Facing infant seat, forward-facing convertible seat and belt-positioning booster
For easy entry and exit from the seat
Functions

PROTECTION THAT GROWS
The Eternis S All-In-One car seat offers three stages in one-easy to use car seat, suitable from 4 lbs. up to 120 lbs., or 57 inches tall. First used as a rear-facing infant seat up to 50 lbs., then as a forward facing convertible seat and lastly as a belt positioning high-back booster seat. With seamless transitions between modes, the Eternis S offers versatile protection that lasts all the way through your child’s first 10 years of age..

12-POSITION HEIGHT ADJUSTABLE HEADREST
The 12-position, height-adjustable headrest of the Eternis S and Eternis S with SensorSafe offers comfortable protection as your child grows. The integrated no-rethread harness adjusts with the headrest movement so there’s no need to reconfigure the harness as your child moves up in the seat.

3-POSITION RECLINING HEADREST
Patented 3-position reclining headrest helps prevent the child's head from falling forward while asleep, keeping the head and neck in a safe position and ensures a comfortable sleeping position.

LINEAR SIDE-IMPACT PROTECTION (L.S.P.)
The L.S.P. System of the Eternis S and Eternis S with SensorSafe extends on the door facing side of the installed car seat and offers increased safety during a side-impact collision. The L.S.P. System reduces the forces of an impact in the event of a side-impact collision by approximately 25% when compared to the same car seat without L.S.P. extended..

IN-SEAT RECLINE
The in-seat recline feature of the Eternis S adjusts to multiple positions, helping to provide a correct ergonomic positioning, a better fit, and extra legroom, allowing your child to safely ride rear-facing longer - up to 50 lbs. The seat comfortably angles the child to help minimize head slump and keep airway open, for a custom, cradled fit

INNOVATIVE ONE-PULL LATCH REMOVAL SYSTEM
For easy installation and removal from the vehicle seat.

REMOVABLE CUP HOLDER
removable cup holder can be positioned on either side and is dishwasher safe for easy clean up.

SENSORSAFE TECHNOLOGY
The Eternis S is also available with SensorSafe Technology built into the chest clip. SensorSafe Technology provides essential alerts when unsafe conditions arise, like if a child unbuckles themselves while the vehicle is in motion; if the back seat has become too warm or too cold, if a child has been seated for too long, and if the driver accidentally leaves the child behind after the vehicle has been switched off. These alerts are provided through an installed vehicle receiver and a user-friendly smartphone SensorSafe App, which also provides guidance on installation, FAQ’s, a directly line to customer service and more. Select the Eternis S with SensorSafe for this additional safety feature.
FAQs
Will this car seat fit my child?
The Eternis S is designed for children between 2.3 -54.4kg (4-120 lbs.) with a height between 43.2-144.8 cm (17-57 inches).
Will the Eternis S convertible car seat fit my vehicle?
CYBEX does fit checks on a variety of vehicles. Due to variations in make, models, and years of manufactured vehicles, it is encouraged to try the seat in your vehicle at a retail location nearest you. You should try both rear facing and forward facing modes and in different locations (outboard rear seat, vs middle seat). CYBEXCYBEX recommends getting your seat checked by a Certified Child Passenger Safety Technician. You can find this free service by visiting www.safekids.org to find a seat check nearest you.
Does the Eternis S convertible car seat have an expiration?
Every car seat has an expiration due to Regulatory changes and technology enhancements in child passenger safety. The Eternis S convertible car seat has been certified for 10 years of use. Once your car seat has reached its expiration date, we recommend recycling the seat by contacting your local community recycling center.
How much does the Eternis S convertible car seat weigh?
The weight of the car seat (excluding the infant positioning pillow is 11.8 kg (26 lbs)
How big is the Eternis S convertible car seat?
The seat will vary in height and depth depending on the recline angle and headrest position. The seat with headrest down and in the upright position is 63.5 H x 51 W x 64.2 cm (25.5” H x 20” W x 25.3” D inches)
Eternis S with SensorSafe All-In-One Car Seat
The Eternis S with SensorSafe monitors the well-being of the seated child through the smart chest clip that is synced with the installed vehicle receiver and the caregiver's smartphone; and while originally developed to help prevent the rising number of infant hot car deaths, the Cybex design of this technology has been expanded to ensure safety for children in a range of additional situations.
The Eternis S with SensorSafe still provides that essential alert when the caregiver accidentally leaves the child behind in the car, but also alerts the caregiver if a child unbuckles themselves while the vehicle is in motion; if the back seat has become too warm or too cold; and if a child has been seated for too long —all through a user-friendly app, that also provides guidance on installation, how-to videos, FAQ’s and other useful information to help prevent car seat misuse.
- 5-point safety harness with SensorSafe Technology integrated in the chest clip
- 12-Position Adjustable Headrest offers comfortable protection as your child grows. The integrated no-rethread harness adjusts with the headrest movement so there’s no need to reconfigure the harness as your child moves up in the seat.
- Adjustable Linear Side-impact Protection (L.S.P. System) absorbs up to 25% more impact forces in the event of a side impact.*
- Energy Absorbing Shell to help reduce the forces felt by the child in a collision.
- Magnetic Buckle Holder for easy entry and exit from the seat.
- 10-position one-hand adjustable recline helps ensure proper angling and best fit to your vehicle seat.
- Removable newborn inlay provides additional support for babies from 4 lbs. to 11 lbs.
- The removable cup holder can be positioned on either side and is dishwasher safe for easy clean up.
- Innovative one-pull LATCH removal system for easy transitions.
- 2 Year Warranty
- Engineered in Germany
- SensorSafe Technology available on select models ONLY
- SensorSafe is compatible with most vehicles 2008 or newer with an OBD II port. For some electric vehicles, contact Parentlink as an additional adapter may be needed
*when compared to the same car seat without L.S.P. extended
Product Details

Package Length:Rear-Facing: 32" Forward-Facing: 25.25” (PKG: 23.4")
Package Width:Rear-Facing: 22-25" Forward-Facing: 19.75-22” (PKG: 20.4")
Package Height:Rear-Facing: 19" Forward-Facing (Fully upright): 25.5-29.5" (PKG: 26.3")
Package Weight:PKG: 29.5 lbs
Product Weight:26 lbs.
Features
The CYBEX Eternis S with SensorSafe All-In-One Car Seat offers 10 years of use in one easy-to-use package – making it the only car seat your child will need, from birth and beyond. The SensorSafe technology integrates important next-gen safety features into the chest clip of the car seat to alert you when unsafe situations arise.
The Eternis S offers an adjustable Linear Side-impact Protection (L.S.P. System), which absorbs up to 25% more impact forces in the event of a side impact collision* and a patented 3-position reclining headrest, which helps prevent the child's head from falling forward while asleep, guiding the head and neck into a safe position. These features, combined with a steel reinforced frame for strength and durability provide advanced child safety protection and peace of mind.
Suitable from 4 lbs. up to 120 lbs., the Eternis S offers 3 stages of protection – as a rear-facing infant seat up to 50 lbs., a forward facing convertible seat and then as a belt-positioning booster that lasts through your child’s first 10 years of age.