This high back booster seat is attached to the car's ISOfix points...

... and the child is restrained with  the adult seat belt.

The seat belt must be threaded through the (usually red) hook at the bottom of the headrest. This hook needs to be about an inch above the shoulder.

In this non-ISOfix high back booster, the seat belt restrains the child and the seat at the same time.

Some boosters are secured into the car by clicking them into the ISOfix points. This one has rigid arms...

... and this one has hooks on soft straps.

Once the hooks are attached, pull the straps at the front to secure the seat into the car.

Some booster seats are deliberately designed not to have belt horns, to prevent misuse...

... but most boosters do have horns and the seat belt must go underneath both of them, so that the lap belt sits low down on the hips.

High back boosters and booster cushions which don't have ISOfix must be strapped in with the seat belt when the child is not in the car. In the event of a crash, or even if you have to brake sharply, they can become dangerous projectiles that can injure the driver and other passengers.

The pictures on this website show installation methods for the most common types of car seats, and we have used many different ones. But car seats vary and these pictures should not be used as a replacement for the manufacturers' instructions. It is very important that you read the user manual carefully and only install your seat according to its own specific instructions.