HC-SR04 ultrasonic sensor

The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object like bats or dolphins do. It offers excellent range accuracy and stable readings in an easy-to-use package. It operation is not affected by sunlight or black material like Sharp rangefinders are (although acoustically soft materials like cloth can be difficult to detect). Similar in performance to the SRF005 but with the low-price of a Sharp infrared sensor.
Power Supply :5V DC 
Quiescent Current : <2mA 
Effectual Angle: <15° 
Ranging Distance : 2cm – 500 cm/1" - 16ft 
Resolution : 0.3 cm