The digital EV3 Ultrasonic Sensor generates sound waves and reads their echoes to detect and measure distance from objects. It can also send single sound waves to work as sonar or listen for a sound wave that triggers the start of a program.

?Can also be used on Ev3?
Using the NXT brick, the ultrasonic sensor is able to detect an object and measure its proximity in inches and centimeter. You will need a connector cable, which is included in the 9797 Base Set.