LG TONE-FP9 Owner's Manual page 19

3 Connect the USB Type C™ side of the USB-C™ to AUX cable to the
charging case. (The USB-C™ to AUX cable does not support the
charging function.)
4 Connect the AUX side of the USB-C™ to AUX cable to a device that
you want.
NOTE: Deactivate the Plug and Wireless Mode to reconnect the
earbuds to the Bluetooth device that was previously connected.
If the Plug and Wireless Mode is turned on, the earbuds and the LG TONE
Free app are disconnected.
The Plug and Wireless mode does not support the call function.
The Plug and Wireless mode may not be compatible with some
devices. In airplane models in which the AUX terminal is divided into
left and right channels, an adapter (separately sold) may be necessary.
If you use the Plug and Wireless mode for a long duration, the battery
of the earbuds (including the charging case) may drain faster than
when physically connected to a smartphone.
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