This is a standard square steel cut with 0.5 inch (12.7 mm) square, which is widely used in machinery, construction and civil engineering fields, such as frame materials and reinforcing materials. A popular steel material that is also popular as an iron hisa for charcoal grillanting. It will remain black iron oxide on the surface. Because it is made of industrial steel, it has an oil for cutting and thinner. Also, because of the nature of the iron material, rust is prevented. Please be aware that the product sold may also have some rust in some cases. If you use it as a cookware, please wash it and harden yourself. ※Returns and exchanges cannot be accepted.