Hand saws are also called hack saws, and they are used for cutting metals and the like. The main body is bow-shaped, and it is used with a thin, narrow blade attached. Tension is applied to the blade by turning the included screw; and when force is applied, the blade becomes hard to bend, enabling hard items to be cut. The grip is covered with rubber and has a shape that allows force to be easily applied, enabling efficient work. By changing the blade according to the material, materials such as resin or wood too can be cut easily in addition to metals such as iron, stainless steel, and aluminum. Bimetal and cobalt are used for hand saw blades, giving them high durability and thus long life and making them safe as they do not easily shatter when bent.