The EYE Safety Helmet comes with an ultrasonic probe located at the top of the helmet, which can detect large incoming obstacle. In the times of emergency like this, the built in alarm will warn user to take preventive measure through the earphone comes with it. Thus preventing user from getting blunt force injury.The height of construction site is about 4 meters, the workers' height is about 1.8 meters. If a stone falls on a man's head, it need 0.5 seconds through the mathematical formula that "x=1/2gt^2";. And the man's reaction is fast than 0.5 seconds.