The nXt "Otto" is a green alarm clock (Ø 9.5cm). When the alarm goes off you hear a beep signal which is getting faster. The alarm clock has a snooze function and a small light. You turn on the light by pressing the snooze/light button. With the the silent movement this alarm clock wakes you up, not keeps you up! This clock runs on 2x AAA battery (not included).