This stones are made from pure aluminum, sintered at high temperature over 1800°C with no bonds. These stones are resistant to change in shape and are extremely hard. They are widely used for sharpening and flattening hard metals as well as glass, quarts, porcelain etc. Outstanding resistance to wear, leave very little grit on sharpened blade, more economical to use then other comparable tools. The Stones can made in various shapes such as rectangle, triangle, square, flat, half round, round, knife, also they can be made in the shape of wheels.