NOYAFA NF-168 - Manual (Page 13)

Other functions
(1) Low-voltage hint function
When the battery voltage is low, push the function button
to “scan” or “test” , at this time, both the scan indicator and wire
sorting indicator will flash, which means the battery should be
replaced.
(2) Earphone function
The earphone can be worn in noisy environment for operation
so as to avoid external interference.
(3) Volume adjustment function
Turn volume adjustment switch on the receiver when tracing
cable to adjust the volume to the appropriate degree.
(4) Floodlight function
The side floodlight can be started at night or in dark.
The floodlight turns on so as to facilitate your normal operation.
(5) Wire sorting directly with switch
Connect the line to be tested with transmitter and switch,
then get the result from flashlights.
Your excellent helper in cable test! 09