An Ultrasonic Flaw Detector is a non-destructive testing device used to identify internal defects in materials. It works by emitting high-frequency sound waves into the material and measuring the time it takes for the waves to return. Any irregularities, such as cracks or voids, will reflect the sound waves differently, allowing operators to detect flaws. These detectors are commonly used in industries like manufacturing, aerospace, and construction to ensure the integrity of components. They are valued for their accuracy and ability to inspect a wide range of materials, including metals, plastics, and composites, without causing any damage.