Two Power Source – This clock will automatically work in power saving mode when powered only by 3 AAA batteries（not included. When power saving mode is on, the LED will turn off automatically 15s after your last operation and can be awake by a slight tap, snap, or clap. If you want the LED to stay on, please plug in the power cable (included) and power it with a 5V/1A USB adapter（not included). Alarm and Snooze – Long press “ALARM” to set alarm time and snooze time. Use “UP” and “DOWN” to adjust the hour and minute. Snooze time is from 1 min to 60 min each time and 3 times in total. Easy to Read – the Digital alarm clock for bedrooms have a big LED numbers, and display brightness can be easily adjusted for personal preference. 12 and 24-hour time display supported. To keep the time and avoid setting all parameters after unplugging the power cable, please install batteries. Adjustable Brightness – If you find the LED too bright at night, you can adjust it to a low level with the “UP” button, long-press the LIGHT button to turn off the LED, or unplug the power cable and make the clock works in power saving mode. Simple Design – The digital alarm clock comes with pure black housing and a clear LED display.   Note: Colour may look different with actual product due to computer or phone screen Size may have differences if require exact or precise measurement talk to us!