Brand new anti-sleep alarm for drivers!
Perfect for anyone who needs to keep alert on duty, like drivers, guards, machine operators, and even students
Works on the study of human body balance
Alerts when the head loweren in the degrees of 15° to 20°

Dimension: 7 X 6.5 cm
Power: 1 X 1.5V button battery
How to use: turn the power on, and wear it on right or left ear. It emitts "Bi-Bi-" alarm when driver tends to fall asleep with his head lowered; there is no sounds emitted when driver keeps normal driving status with eyes looking forward
Notice: for color please refer to the actual product you receive