[USB Powered & Battery Backup]The alarm clock is powered by a wall outlet (adapter not included) and can be powered by 3 AAA batteries (not included) as a backup. In the event of a power outage, the alarm clock runs on battery power and automatically saves the time, date and other settings. Note: Batteries drain quickly and it is recommended to only power the device from the wall outlet. [Two power supply modes-USB/Battery]Connect the digital alarm clock to the power outlet (adapter not included), the alarm clock screen stays on; if the digital alarm clock is powered by the battery battery (not included), the screen automatically sleeps when there is no operation exists, and the screen can be illuminated by pressing any button. Note: Batteries consume power quickly, it is recommended to use a USB power adapter. [Snooze]When the alarm clock digital beeps, touch the top big snooze logo to get an extra 5 minutes nap, it can last for 3 snoozes; And you can long the top big snooze logo for 3s to turn off snooze mode; the top big snooze logo for 3s to stop the alarm today and it still sound day. [3 levels of brightness] the largest button in the middle to adjust the brightness in 3 levels (high/medium/low). [Tip]If the device is powered via USB (adapter not included), the alarm clock screen remains on. When operating on battery power (battery not included), the alarm clock switches to energy saving mode after 13 seconds and turns off the screen, which you can activate by pressing a button or by voice. color:Black Material: Plastic Package Contents: 1 x alarm clock Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.