HP 645 G3 Maintenance And Service Manual page 21

Component
(3) Wireless button
(4) Volume mute button
(5) Fingerprint reader (select products only)
Description
Turns the wireless feature on or off but does not establish a
wireless connection.
A wireless network must be set up before a wireless connection is
possible.
Mutes and restores speaker sound.
Allows a fingerprint logon to Windows®, instead of a password
logon.
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