5pcs HC-SR04 Ultrasonic Distance Measuring Sensor Module for Arduino

features stable performance and accurate distance measurement. It is compare favourably with SRF05, SRF02 and other ultrasonic distance measuring modules. With high precision, ultra-close(2cm) blind area and stable performance. Features: Adopt IO trigger distance measuring, to at least 10us high-level signal. Module automatically sends 8 40KHz square wave, automatically detect whether there is signal return. If there is signal return, output a high level through the IO, the duration of high level is the time of ultrasound from the launch to the return. Distance measurement = (high level time * sound speed (340M/S)) / 2. Discounted at only: US$ 9.21