A NIKATTO combination wrench metric is a versatile and essential tool used in various mechanical and engineering applications. It is specifically designed to work with metric-sized nuts and bolts, which are common in many countries around the world. 
The combination wrench has two different types of ends: an open-end and a box-end. The open-end features a U-shaped design, making it easier to slip onto the fastener. On the other hand, the box-end is closed and has six or twelve points, providing a more secure grip on the fastener. 

This tool allows for flexibility in application since you can use the open-end for quick adjustments and the box-end for applying higher torque when more turning force is required. The combination of these two ends makes it easier to access nuts and bolts in confined spaces where other tools might not fit. Metric combination wrenches are often made from durable and sturdy materials like chrome-vanadium steel to withstand the rigors of heavy-duty use. They come in a range of sizes to accommodate different metric fasteners, usually marked on each end for easy identification. 
This feature allows mechanics, DIY enthusiasts, and professionals to have a comprehensive set of tools, ensuring they can handle various tasks efficiently and effectively. In summary, the combination wrench metric is a valuable tool known for its adaptability, durability, and suitability for metric-sized nuts and bolts, making it a must-have for anyone dealing with mechanical repairs, maintenance, or construction projects.