Sony SRS-ZR7 Help Manual page 199

To enjoy a more dynamic sound
Pull the lever on the bottom of the speaker in the direction of the arrow shown in the illustration below to remove the grille.*
* After removing the speaker grille, do not touch the exposed part of the speaker (speaker units), and keep the removed grille on a flat surface to prevent
distortion.
What you can do with the speaker during playback
You can adjust the volume using the -/+ (volume) buttons.
Hint
After SongPal is downloaded and installed to your smartphone, iPhone, etc., you can use it as a remote control.
Note
Sony is not responsible for any loss or damage to data in a USB flash drive that is connected to the speaker.
Do not disconnect a USB flash drive during operation. To prevent damage to data, stop playback, then turn off the power of the speaker before
disconnecting the device.
Sony does not guarantee correct operation when a USB hub or USB extension cable is used.
When you connect a USB flash drive, the speaker starts reading all the data stored on it. Reading files may take some time.
Operation may become slow depending on the USB flash drive.
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