Electromagnetic Ultrasonic Thickness Gauge is a non-destructive testing (NDT) instrument that uses an electromagnetic acoustic transducer (EMAT) to generate ultrasonic waves in the test material via electromagnetic coupling. The waves reflect from the back wall, and the thickness is calculated based on the ultrasonic velocity and time of flight. It enables non-contact measurement without damaging the surface and is suitable for high-temperature and moving objects, such as hot steel plates and in-service pipelines. With high accuracy and fast measurement speed, it is widely used in petrochemical, metallurgy, aerospace, pressure vessels, pipelines, automotive manufacturing, and research applications.