The Nap Alarm is for anyone who has ever felt drowsy while driving. Some of us have actually fallen asleep only to be awakened by a blaring horn of an on coming car. The nap Alarm is an innovative potentially life-saving anti-drowsiness alarm. The Nap alarm is worn over the ear and has an electronic position sensor which activates when your head nods forward to instantly wake you and alert your passengers. The nap alarm is not only designed for drivers but is also perfect for people who need to be fully alert while on duty. The alarm is great for machine operators, security guards and even students while studying where concentration is required. Uses three AG 13 alkaline button cell batteries included.