Product Description:
HC-SR04 Ultrasonic Sensor 
Power Supply :5V DC 
Quiescent Current : <2mA 
Effectual Angle: <15° 
Ranging Distance : 2cm - 500 cm 
Resolution : 0.3 cm 
Mode of Connection: VCC/ trig(T)/ Echo(R)/ GND
(VCC supply 5V, and GND is ground wire. TRIG is trigger control signal input, ECHO is echo signal output.) 
Quantity: 5pcs

Attention:
The module should be inserted in the circuit before been powered to avoid producing high level of misoperation; if producted, power it again.
The module is not suggested to connect directly to electric, if connected electric, the GND terminal should be connected the module first, otherwise,it will affect the normal work of the module.
When tested objects, the range of area is not less than 0.5 square meters and the plane requests as smooth as possible, otherwise ,it will affect the results of measuring.

Describe:

• HC-SR04 Ultrasonic Sensor Distance Module: using IO trigger for at least 10us high level signal
• This module has stable performance and accurate measurement distance.
• Detection distance: 0.78~196 in/ (2cm~500cm); High precision: up to 0.12 in/(0.3 cm); Detection angle: <15 °.
• This module is fully Compatible with GH-311 anti-theft module.
• HC-SR04 Arduino ultrasonic sensor can send eight 40 kHz and detect whether there is any pulse signal back.If it back, a high level signal will be outputed by IO, and the duration of the signal is the time from sending ultrasonic to returning.