HP ProBook 645 G1 Notebook PC - Manual (Page 24)

Rear (select models only)
Component Description
(1) RJ-11 (modem) jack (select models only) Connects a modem cable.
(2) Serial port Connects an optional device such as a serial
modem, mouse, or printer.
Display
NOTE: Your computer may look slightly different from the illustration in this section.
Component Description
(1) WLAN antennas (2)* Send and receive wireless signals to communicate with wireless
local area networks (WLAN).
(2) WWAN antennas (2)* (select models only) Send and receive wireless signals to communicate with wireless
wide area networks (WWAN).
14 Chapter 2 Getting to know your computer