The tutorial explains the use of a lower removable expander, which has clasps that hook between the teeth and a front bow. It can be turned outside the child's mouth, with a yellow arrow indicating the direction of the turn towards the floor of the mouth. A key is used to turn the expander until it stops, and there's a hole for the next turn. The recommended turning schedule is two turns per week on non-consecutive days, with the option to reduce to one turn per week if the child experiences discomfort.
