Elegoo HC-SR04 Ultrasonic Module Distance Sensor for Arduino UNO MEGA2560 Nano Robot XBee ZigBee, Set of 5 Ultrasonic hc-sr04 distance measuring transducer sensor HC-SR04 consists of ultrasonic transmitter, receiver, and control circuit. When trigged it sends out a series of 40KHz ultrasonic pulses and receives echo from an object. ~Power supply: 5V DC; quiescent current: less than 2mA; effectual angle: less than 15; distance: 2cm500cm; resolution: 0.3 cm~ Package Content: 5pcs HC-SR04 with a little gift