Forward-facing car seats all come with a tether strap, which secures the top of the car seat to an anchor in the back of the car. Every forward-facing car seat is safer (and better able to protect your child's brain and spinal cord) when you use the tether strap.
Are tether anchors required?
Vehicles model year 2000 and newer must have tether anchors in at least three backseat positions. In the backseat of vehicles with only one row of seats in the back (sedans, small SUV's, hatchbacks, etc), all three positions in the backseat must have tether anchors.
Can you use a carseat without top tether?
Rear facing car seats fit just fine in many vehicles that don't include factory-installed tether anchors becuase they don't require a top tether. When the child outgrows their rear facing car seat, familes who drive a pre-21st century vehicle will need to carefully consider the child's next step.