The Grove ultrasonic distance sensor is an ultrasonic transducer that uses ultrasonic waves to measure distance. It can measure from 3cm to 350cm with an accuracy of up to 2mm. It is a perfect ultrasonic unit for distance measurement, proximity sensors and ultrasonic detector This unit has an ultrasonic transmitter and an ultrasonic receiver, so you can consider it as an ultrasonic transceiver. Similar to sonar, when the 40KHz ultrasonic wave generated by the transmitter encounters the object, the sound wave will be reflected and the receiver can receive the reflected ultrasonic wave. It calculates the time from transmission to reception and then multiplies it by the speed of sound in air to calculate the distance from the sensor to the object Features: 3.3V/5V compatible, wide voltage level: 3.2V ∼ 5.2V Only 3 pins needed Wide measurement range of 3cm ∼ 350cm Easy to use grove connector, plug and play