To activate your user-friendly Flashing Blue LED Wooden Cube Digital Alarm Clock with USB, plug into a USB port (cable provided and recommended if using daily). Instructions: Hold down SET button to enter Setting Mode, where you can modify: Year Date Time Format (12-Hour or 24-Hour) Time (Hour & Minutes) Alarms Press SET button to choose display functions: Mode 1 Cycles through Time, Date, and Temperature Mode 2 Displays only the Time Hold down UP button to adjust LED brightness: LO Dimmest setting L3 Brightest setting Press UP button to select Temperature format. Press DOWN button to choose sleep mode ON/OFF. Specifications LED Colors: Blue Printable: Yes Batteries: 3 Replaceable AAA Batteries Dimension: 2.5" cubed Weight: 0.36 lbs