This knife is a deba knife that has not been polished. Its appearance is uneven because it has not been polished. As a result, it is cheaper than polished knives. It is highly valued by people in industries that do not care about the appearance, such as fishmongers and processing companies. It can also be used at home if you do not care about the appearance. If you polish it with polishing powder, the black parts will come off and it will shine silver. However, the unevenness of the surface will not become flat. This knife is useful when used in a slightly larger size for grating or splitting fish heads. The size refers to the blade length.