FORD 2008 F-550 v.4 - Manual (Page 58)

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
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.)
Additional infrared wireless
headphones may be purchased for
use with the system. Also, wired
headphones may be purchased and
plugged in where indicated on the
left and right hand sides of the
system. Refer to Wired
Headphones following.
2008 F-250/350/450/550 (f23)
Owners Guide (post-2002-fmt)
USA (fus)
Entertainment Systems
58