Classification of manual tools used for tightening and loosening bolts and nuts. This covers essential tool groups for machine assembly, equipment maintenance, and parts replacement work in manufacturing sites. Various types are available according to bolt and nut sizes, shapes, and working environments, including spanners, adjustable wrenches, box wrenches, combination wrenches, hex keys, torque wrenches, and pipe wrenches. Distinguished from electric impact wrenches and hydraulic tools, these are limited to manually operated tools that adjust tightening torque through human power. These are basic tools used across a wide range of manufacturing processes, from precision machinery assembly to heavy machinery maintenance.