Koram Multi-function LED Clock Alarm Snooze Alarm Adjustable Brightness Indoor Temperature Calendar (White) Brightness control (High, Mid, low): you can adjust the brightness at night, so that it will not affect your sleep. Run by AC power, build-in Button Cell(CR2032) to avoid reset the time when it disconnect the power. It can be used as a table/desk clock, but also can be hung to act as a wall clock. Energy saving and kind to the environment , no sound is generated Long-distance readable. it is readable easily within 25 meters, which is very different from traditional clocks which can only be used from a short distance.