HP EliteBook 840 G3 - Manual (Page 14)

Component Description
(6) RJ-45 (network) jack Connects a network cable.
(7) Docking connector Connects an optional docking device.
(8) SIM card slot Supports a wireless subscriber identity module (SIM) card.
(9) Power connector Connects an AC adapter.
4 Chapter 2 Getting to know your computer