RoyalTek RN5 - Manual (Page 22)

2. You can view the OS version, GPS firmware version and other system information..
3.6. Volume
1. Tap the Volume icon in the System Menu.
2. Adjust the volume by dragging the wheel.
3. Dragging to left will become mute, and opposite will become larger.
3.7. Backlight
1. Tap the Backlight icon in the System Menu.
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