HC-SR04 Ultrasonic Distance Detection Module.

This HC-SR01 ultrasonic distance sensor allows measurements from 2cm to 400cm with a precision of up to 3mm. The measurement cone angle is approximately 15°. The HC-SR04 sonar includes an ultrasonic transmitter, an ultrasonic receiver, and a control circuit. Sending a 10 µs pulse as input prompts the sensor to return a pulse width proportional to the distance.