Hi Rachael, Thank you for your enquiry. When fitting a child into a booster (with a built-in harness), always refer to the manufacturer’s instructions. In particular, with the Nani I Max Harnessed Booster seat It is important to remember to remove the harness once the child has reached the weight limit of 18kg. A booster seat can be used for an older child. Use your child restraint for as long as your child fits it, as it offers more protection in a crash. For a booster seat to offer maximum safety, it must be used with the lap belt always over the child’s hips and thighs, never across the abdomen. The sash belt must be diagonally across the chest, passing over the child’s shoulder near the neck. However, never use a booster seat with a lap belt only unlesss used with a child harness. If you follow the link https://www.babyonthemove.co.nz/store-locations/ this will take you to our online store finder where you can find contact details for your nearest Baby On The Move Store. Here, one of our expert Car Restraint Technicians can assist in helping you clarify if this is the right car seat for you and your child and answer any further questions you may have. We hope this has helped with your query.