Large LED Display & Snooze Function: This digital alarm clock has a large 6.7-inch LED display that is easy to read, with a slim body that can also be used as a mirror. Adjustable Brightness: Clear and comfortable viewing, with automatic dimming at 6:00pm. The LED light will always be on when the USB cable is plugged in. When using battery mode, the screen will automatically turn off after 10 seconds. You can voice activate the screen, or press any key to turn it on. Press and hold "LIGHT/SNOOZE" for 3 seconds in any mode to turn off the screen. Powered by USB or Battery: The alarm clock can be powered by a USB cable or 3 AAA batteries (not included). Note: If the alarm clock is running on battery, the alarm clock will be on for 5 seconds and then off, you can activate the boot screen by clapping your hands.