Britax Marathon ClickTight vs Cybex Eternis S

Both are convertible car seats — here are their published manufacturer specs side by side.

This compares published manufacturer specs — not safety or fit advice. The seat's manual, your vehicle's manual, NHTSA's tools and a certified CPST are the fit-and-safety authority; always check them before installing.

Spec	Britax Marathon ClickTight	Cybex Eternis S
Stage	Convertible	Convertible
Narrow (3-across)	–	–
Extended rear-facing	–	✓
FAA-approved	✓	✓
Lightweight / travel	–	–

How they differ

• the Cybex Eternis S lists extended rear-facing (a higher rear-facing weight limit, ~40-50 lb); the Britax Marathon ClickTight doesn't

Where to buy

Check the Britax Marathon ClickTight price on Amazon →

Check the Cybex Eternis S price on Amazon →

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FAQ

What's the difference between the Britax Marathon ClickTight and the Cybex Eternis S?
The Britax Marathon ClickTight is FAA-approved for aircraft; the Cybex Eternis S is extended rear-facing, FAA-approved for aircraft. Both are convertible car seats.

Which is right for my car and child, the Britax Marathon ClickTight or the Cybex Eternis S?
That depends on your specific vehicle and child — this page compares published manufacturer specs only, not fit or safety. Check the seat manual, your vehicle manual, NHTSA's car-seat finder and ideally a certified CPST before deciding.

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