This category encompasses non-destructive testing equipment that inspects and evaluates internal defects and material properties without destroying products or structures. It includes ultrasonic flaw detectors, eddy current testing equipment, magnetic particle testing devices, penetrant testing equipment, radiographic testing apparatus, and visual inspection instruments. These essential quality control inspection devices are used in manufacturing processes and maintenance inspections for weld defect detection, material fatigue crack identification, thickness measurement, and corrosion inspection, and are clearly distinguished from destructive testing equipment and general measuring instruments.