Category for specialized measuring instruments that perform high-precision measurement of contour shapes of parts and products in manufacturing. Includes contact and non-contact contour measuring machines, surface profile measuring instruments, profile measuring machines, and straightness measuring devices. Used for shape accuracy inspection of machined parts, contour measurement of molds, cutting tool edge shape measurement, and quality control of automotive parts. Unlike simple length measurement, these instruments specialize in digitizing and evaluating complex two-dimensional and three-dimensional contour lines, focusing on precision measurement of curved surfaces and complex shapes that are difficult to measure with calipers or micrometers. Essential inspection equipment for quality assurance of parts manufactured by NC machining centers and CNC lathes.