Sparkfun SEN-15569 Ultrasonic Distance Sensor – HC-SR04
This budget Ultra-Sonic range finder will read between 2cm and 400cm with an accuracy of up to 3mm. The board runs at 5V (DC) and uses around 15mA. With a reading angle of 15 degrees, this is great for inexpensive range finding for obstacle avoiding robots or reading objects passing on a conveyor belt ETC.
This module packs a control circuit, ultrasonic transmitter and a receiver.
This sensor has additional control circuitry that can prevent inconsistent “bouncy” data depending on the application.