Working Principle: electronic balance.
A gravity switch inside the alarm monitors the angle of the driver's head. It fits on the ear of a driver, when the driver feels sleepy during his driving or on a long trip, and his head nods forward, the alarm will be on and arouse the alert of the driver and passengers. It stimulates the nerve to be exciting and eliminates the sleepy feeling, therefore to avoid traffic accidents.

Alarm Angle: 15-20 degree
Built-in loud intensity: 100db
Bettery type: 2pcs AG12 batteries
lifetime of one couple batteries: one year
standard color: yellow, green, red, blue
Packing: blister card