Pick how you're putting it in. Each way is from the maker's manual.
Base with LATCH
Where it can go: Rear-facing only; the vehicle seat must face forward. Do not place it on a front seat with an airbag; the back seat is safest. If all load leg requirements cannot be met, choose another seat, install the base with the load leg stored, or install the carrier without the base.
1With the car on level ground, take the LATCH connectors out of storage by pulling the red strap, and unfold the load leg until it clicks open (its indicator turns green).
2Position the base on a rear vehicle seat in an approved LATCH location and adjust the leveling foot until the ball sits in the green zone of the level indicator.
3Squeeze the lock-off release and lift the lock-off open.
4Attach both LATCH connectors to the lower anchors until each clicks, and pull firmly to check.
5Push the base against the seat back and pull the LATCH adjuster strap until it is just snug, then press the lock-off down until it locks.
6Squeeze the load leg adjustment button and extend the foot to the floor, locking it in the first hole that holds it firmly without lifting the base off the seat.
Check it before you drive
Grab the base at the belt guides: it should not move more than 1 inch (2.5 cm) in any direction; if it does, open the lock-off, tension the strap a little more and try again.
If the lock-off will not lock, loosen the LATCH strap slightly.
The level indicator ball must be in the green zone; if it is in the red zone, remove the base, adjust and reinstall.
There should never be a gap between the load leg foot and the floor, and the load leg should never push the base off the seat.
Retold from Cybex manual (PDF). Your vehicle's manual also says which seats have LATCH anchors. When in doubt, a certified child passenger safety technician can check your install.
The carrier on and off the base
Clicking it onto the base
1Make sure the handle is locked in position A.
2Lift the carrier by the handle and drop it into the base until you hear a click.
3Lift up on the carrier to check it is locked; the window on top of the load leg turns green when it is attached.
4Pull out the side impact protector (L.S.P.) on the side next to the car door.
The maker warns: Check the handle is locked in position A before lifting by it; an unlocked handle could move and the baby could fall out. Keep the handle in position A while the seat is in the car.
Rear-facing only; the vehicle seat must face forward. Do not place it on a front seat with an airbag; the back seat is safest. If all load leg requirements cannot be met, choose another seat, install the base with the load leg stored, or install the carrier without the base.
How do I know the Cybex Aton M is installed right?+
Grab the base at the belt guides: it should not move more than 1 inch (2.5 cm) in any direction; if it does, open the lock-off, tension the strap a little more and try again. If the lock-off will not lock, loosen the LATCH strap slightly. The level indicator ball must be in the green zone; if it is in the red zone, remove the base, adjust and reinstall. There should never be a gap between the load leg foot and the floor, and the load leg should never push the base off the seat.
