Specialized measuring instrument for accurately measuring the rotational speed of rotating machinery in manufacturing sites. Used for measuring spindle rotation speed of machine tools, motor rotation speed, and operational verification of pumps and fans. Available in contact type (mechanical tachometer) and non-contact type (optical, laser). Essential for machining condition setting of CNC lathes and milling machines, rotating equipment diagnosis in facility maintenance, and product inspection in quality control. Capable of high-precision measurement in rpm (revolutions per minute) units, playing an important role in manufacturing process optimization and preventive maintenance of equipment. Clearly distinguished from vibration meters and thermometers by measurement target, positioned as a dedicated measuring instrument for rotating bodies.