DUAL USB PORT -- One USB port connected with DC adapter power. Another one charging your cellphone, tablet, mp3 players or other smart device. Convenient and practical. Great Thanksgiving and Chirstmas gift. OUTLET POWERED AND BATTERY BACKUP -- Power by DC adapter (Included). Insert 2* AAA batteries (Not Included) can be memorize time and alarm in case of power outages. During the backup battery, NO time display and NO alarm sound. EASY TO SETUP -- Simple alarm clock with 4 independent buttons and 2 adjustment knob on the back, clearly marked. You will hardly need instructions when setting the time or alarm. ADJUSTABLE VOLUME AND SNOOZE -- Comes with an alarm volume switch which can be adjusted to 30-90 DB. Touch-style snooze button easy to press even when half-sleeping, alarm will be last around 3 minutes until using snooze. (10 minutes interval). LARGE LED DIGITAL WITH DIMMER -- 5.5'' led clocks with 0-100 level adjustable LED brightness enables you to set the display as your like. To sleep well, you can adjust the screen to the dimmest(0); and adjust the screen to the brightest(100) at daytime. 12-24 Hr display suitable for different people.