The Nap Zapper is the guardian angel for drivers. This product can protect you and your passengers from accidents due to drowsiness. The Nap Zapper is worn over the ear and has an electronic position sensor. When your head nods forward, it sounds a loud alarm/vibration to instantly awake you and alert your passengers. And this is ideal for students burning the candle at both ends, or for drivers on long stretches of boring road that you know too well. Also security guards, machine operators, or even those watching telly and wanting to maintain correct. The spec as below: A. Weight: 15g B. Size: Length 70mm X Width 60mm X Thickness 15mm C. Type: Sound and Vibration D. Color: Black, blue etc. E. Power: LR14(1.5V X 3) Battery Remark: With 9pcs batteries totally, while 6pcs of batteries attached in additionally(option) F. Alarm Angle: 15 - 30 (Adjustable) G. Rating for the Voice Pressure: 1 cm away from the voice hole >85DB H. Patent: Applied for Design Registration (E0610158E) I. Certification: CE