Nap Alarm is an innovative, potentially lifesaving anti-drowsiness alarm. It is worn over the ear and has an electronic position sensor. When your head nods forward, it sounds a loud alarm to instantly wake you and alert your passengers. The Nap Alarm is not only designed for drivers, it is also perfect for people who need to be fully alert while on duty, for example, security guards, machine operators and even students while studying or where concentration is required. Put it behind your right ear, Alerts when the head lower in the degrees of 15° to 20°. Especially suitable for long-distance driving or night driving. ON / OFF switch. Powered by AG3 button cell batteries(included). Driver safety alarm can help prevent accidents caused by driver's sleep when driving. It is especially suitable for long-distance driving or night driving. It is guardian angel for drivers. Easy to use and comfortable to wear for a long time Color:Black Weight :Approx 14 g Size :Approx 5.8*5.3cm Usage directions: Wear it on the right ear properly as illustrated Turn on the switch Examine whether it is in the normal operation:it beeps when you are leaning your head forward and makes no sound while sitting straight , it is at normal state Please turn off the swith and put it away when you do not use it Keep it away from High temperature and damp