How do I use the belt positioning clip for backless booster mode?

The belt positioning clip must be attached to the slot on the bottom of the base. Insert the loop end of the strap through the slot exactly as shown, pass the clip and strap through the loop end, and pull the strap up. After buckling your child in, slide the clip onto the vehicle's seat shoulder belt and adjust it to fit snugly at the top of the child's shoulder.