Ford F-650 Owner's Manual page 101

Seating and Safety Restraints
Children and booster seats vary in size and shape. Choose a booster that
keeps the lap belt low and snug across the hips, never up across the
stomach, and lets you adjust the shoulder belt to cross the chest and rest
snugly near the center of the shoulder. The drawings below compare the
ideal fit (center) to a shoulder belt uncomfortably close to the neck and a
shoulder belt that could slip off the shoulder. The drawings below also
show how the lap belt should be low and snug across the child's hips.
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.
101
2012 F-650/750 (f67)
Supplement, 2nd Printing
USA (fus)