Features
Output signal: Electric frequency signal high level 5V low level 0V.
Sensor angle: Not more than 15 degrees
Detection distance: 2cm~450cm
High precision: Up to 3mm
Mode of connection: VCC / trig(T) / echo(R) / GND
Module Working Principle:
Adopt IO trigger through supplying at least 10us sequence of high level signal
The module automatically send eight 40khz square wave and automatically detect whether receive the returning pulse signal
If there is signals returning through outputting high level and the time of high level continuing is the time of that from the ultrasonic transmitting to receiving
General Specs
Model HC-SR04
Material RF4  
English Manual/Spec Yes
Working voltage  5V (DC)
Static current Less than 2mA
Download Link http://www.ic5188.com/PDF/HC-SR04.rar 
Dimensions 4.5 x 2.0 x 1.3 cm
Weight 10 g