Ultrasonic testing is based on transmitting high frequency sound waves to materials and receiving them back in order to detect any discontinuities. Probes with pulser/receiver speciality are being used to send sound waves. A probe connected to an ultrasonic testing device sends sound waves into the material. The sound waves pass through the material and reflect back to the probe. With a discontinuity found, sound waves will return to the probe before the distance is complete, this will show a discontinuity was there.