FORD 2009 Ranger v.1 - Manual (Page 113)

If the booster seat slides on the vehicle seat, placing a rubberized mesh
sold as shelf or carpet liner under the booster seat may improve this
condition. Do not introduce any item thicker than this under the booster
seat. Check with the booster seat manufacturer’s instructions.
The importance of shoulder belts
Using a booster without a shoulder belt increases the risk of a child’s
head hitting a hard surface in a collision. For this reason, you should
never use a booster seat with a lap belt only. It is generally best to use a
booster seat with lap/shoulder belts in the back seat.
Move a child to a different seating location if the shoulder belt does not
stay positioned on the shoulder during use.
Follow all instructions provided by the manufacturer of the booster seat.
WARNING: Never place, or allow a child to place, the shoulder
belt under a child’s arm or behind the back because it reduces
the protection for the upper part of the body and may increase the risk
of injury or death in a collision.
2009 Ranger (ran)
Owners Guide, 1st Printing
USA (fus)
Seating and Safety Restraints
113