Car seats suitable from newborn can be grouped into either 0-4 year or 0-8 year types. Both are used rearward facing to start with as per the latest Australian Standards for newborns. Later on, once baby's shoulder reaches the lower height marker, the seat can be turned to frontward facing and is used with an internal harness until the child's shoulders reach the upper height markers on the seat which is approximately 4 years old. The 0-8 year car seats can then convert to car booster seats and use the car seat belt itself to secure the child. Both types are classed as a convertible car seat.