It is an Ultrasonic Distance Sensor v2.0 i.e. a transducer that utilizes ultrasonic waves to measure distance; moreover, it is a non-contact distance measurement module that works at 40 kHz and can measure from 3 cm to 350 cm with an accuracy up to 2 mm.The Grove – Ultrasonic Ranger is a perfect ultrasonic module as proximity sensor, as ultrasonic detector, for distance measurement, and smart car system. You can do various projects using this sensor.

DATA SHEET : https://files.seeedstudio.com/wiki/Grove_Ultrasonic_Ranger/res/Grove-Ultrasonic_Ranger_WiKi.pdf