Piezoelectric transducers (PET, Probes, PEP) are used in ultrasound NDT, acting as an emitter and receiver of an ultrasonic pulse processed by ultrasonic flaw detector. The principle of the PEP is based on the piezoelectric effect - the phenomenon of the emergence of electrical polarization under the influence of mechanical stresses. Type of probes - Ultrasound, Eddycurrent, Resonant, Impedance, Impact, Chord produsing special converters probes is possible: • for control of railway rolling stock parts; • inclined contact, combined probes for monitoring the bending of pipes; • focusing and with a flat radiating surface for immersion control of disks made of titanium alloys and other parts and blanks; • for the control of aircraft blades; • wide-grasping; • on phased arrays for diffraction-time monitoring by TOFD • Electromagnetic-acoustic transducers (EMAT).