Ultrasonic Receiver+Transmitter on Board. The HC-SR04+ is a Wide Voltage Operation : 3V-5.5V. Ultrasonic Ranging Module. The Module's External Dimensions and Software are Fully Compatible with the Old Version of the HC-SR04. Industrial Grade MCU, -20°C-80

The HC-SR04 is an affordable, popular 4-pin ultrasonic distance sensor that measures distances from 2 cm to 400 cm with 0.3 cm accuracy using sonar waves. It works with microcontrollers like Arduino by emitting a 40 kHz sound burst and timing how long the echo takes to return.

VCC: Connects to 5V DC power.
Trig (Trigger): Input pin to send a 10-microsecond pulse to start the sonar.
Echo: Output pin that goes high for the duration of the sound wave's round trip.
GND: Connects to system ground.