CHKOSDA Digital Led Clock Wall Alarm Digital Calendar Alarm Clock Count Down Timer(red) 9.6 inch red LED display board(diagonal) with 2 inch tall & clear single digit. It is long-distance readable, which is big different from traditional clocks. 3 level brightness control, manually select brightness according to ambient light. Even in the lowest brightness, it is long-distance readable and clear in the dark. The LED light dont disturb your sleep. The clock also can show calendar and temperature. There is a SNOOZE key to scan the basic info about the clock, display sequence: time-&gt; temperature-&gt;date-&gt;alarm group-&gt; snooze time Use the adapter connect to the AC/DC electric power. It also can used the backup battery to backup what you set, don't worry you will lost all the setting after power cut suddenly( NOTICE: the battery cell only used as backup time, not for display!) The size of clock: 9.4 inches (L)3.1 inches (H)2.3 inches (W). The clock has protection mechanisms, if you can't turn it on, please cut off the power and take out the CR2032 battery and press the "Reset" key for 5 seconds to activate