Ford 2009 Flex Owner's Manual page 49

Battery replacement
Batteries are supplied with the remote control unit. Since all batteries
have a limited shelf life, replace them when the unit fails to control the
DVD player.
Remove the screw and unlatch the battery cover to access the batteries.
The remote control unit uses two AAA batteries which are supplied with
the unit.
Headphones
Wireless headphones
WARNING: The driver should never use the headphones while
driving the vehicle. Using headphones may prevent the driver
from hearing audible warnings such as horns or emergency sirens,
which could result in a crash causing serious injury. Give your full
attention to driving and to the road.
Your FES system is equipped with two sets of battery powered, infrared
wireless headphones. Two AAA batteries are needed to operate the
headphones. (Batteries are included.)
2009 Flex (471)
Owners Guide, 2nd Printing
USA (fus)
Entertainment Systems
49