Alarm Clocks, Ubetter Wooden Design Decor Desktop Digital Alarm Clock with USB Charing And Time/Calendar/Temperature Display With DC Adapter & USB Cable - Size: 120mmx80mmx80mm Black/White LED Display can be set to be Sound Activated (clock's still working), OR stay on all the time. If sound activated, display turns off after 15 seconds. You clap hands/make a sound/simply touch the clock to activate the display to read time. Brightness adjustable (3 options, and is limited to display alternating mode). Clock can set up to 3 alarms. Clock is made of MDF wood (not real wood) and graining coating. Size:120mmx80mmx80mm Power Supply: 3 AAA batteries (not included) or USB powered (USB charger not included). AAA batteries and USB power supply can be used simultaneously, and batteries act as a backup. Built-in AG3 batteries serve to keep settings in case of power failure (AG3 batteries cannot be changed).