Standard compliance label
There are 3 standards to look for. See "Car seat standards", below.
This holds the adult safety belt tight when it’s used to install the seat or secure the child into a booster seat. A locking clip is a good idea, even though it's not required by the standards. Some restraints don’t need one – so check the instructions.
This stops the child restraint tipping forward in a crash. The tether strap must be used for all restraints (rear- and forward-facing) that comply with the Australian/New Zealand standard – otherwise their safety performance will be compromised. Many forward-facing US restraints also use a tether strap, and the latest Isofix standard includes a tether strap. A tether strap doesn't necessarily make a seat safer than a seat designed without a tether, but if the seat has one it must be used - not using it will risk serious injury to the child, or worse.
Well-padded side wings can help protect the child in a side-on crash. Many wings are height-adjustable so they can “grow” with the child.
Reclining the seat
Many forward-facing and booster seats can be reclined to create either a better fit to the car seat, or to allow your child to sleep more comfortably and safely without slumping forward. Some seats require the recline angle to be chosen before the seat is installed, which will be inconvenient if you need to adjust the angle often. Some seats allow the angle to be adjusted after installation, using a lever or button.
A seat may claim to be suitable for children up to a certain weight but a tall child can grow out of a seat before then. Some forward-facing seats and booster seats have adjustable seatbacks that can be raised as the child grows.
Isofix and LATCH
Many late-model cars designed for sale in Europe are fitted with Isofix mounting points. An Isofix-compatible car seat can be snapped into the rear-passenger-seat frame instead of being held by the car's safety belt – so Isofix reduces the likelihood of a seat being installed incorrectly. The US has a similar system called LATCH (Lower Anchors and Tethers for Children). Isofix and LATCH seats will fit each other's mounting points.
Make sure the lining is easy to remove and washable. To protect your car's seat coverings look for a restraint with a mat underneath. Or you can keep a towel in the car instead.