SunFounder 5 pcs Ultrasonic Module HC-SR04 Distance Sensor for Arduino UNO MEGA R3 Mega2560 Duemilanove Nano Robot Rapsberry Pi 3 B+, 2 & RPi Model B+ XBee ZigBee Ultrasonic hc-sr04 distance measuring transducer sensor, it consists of ultrasonic transmitter, receiver, and control circuit. HC-SR04 Ultrasonic Sensor Distance Module: using IO trigger for at least 10us high level signalWhen triggered it sends out a series of 40KHz ultrasonic pulses and receives echo from an object. Hc-sr04 Test Distance following formula: L = 1/2  T  C ( L is the distance, T is the time between the emission and reception, and C is the sonic speed) Power Supply : 5V DC; Quiescent Current : &lt;2mA,; Effectual Angle: &lt;15 ; Detection Distance : 2cm~450 cm; Resolution : 0.3 cm Package Content: 5 HC-SR04 Ultrasonic Sensors , 10 Female-Male Dupont Cables , 10 Female-Female Dupont Cables , 1 Exquisite package box