Lexus 2004 LS430 Owner's Manual page 186

OCCUPANT RESTRAINT SYSTEMS
Center rear seat
16L279
To move the head restraint forward, pull on the top. To
move the head restraint forward or rearward, pull or push
on the top.
The head restraint is most effective when it is close to your
head. Therefore, using a cushion on the seatback is not
recommended.
CAUTION
After adjusting the head restraint, make sure it is locked
in position.
166
16L278b
Push the button to return the head restraint to its original
position.