Laboratory ball mills are designed to crushing medium, hard and soft powdery materials to powder. Ball mills depending on the number of rolls can be equipped with two rotating rollers (double roll mills), three rolls (3-roller mills), etc., or depending on the number of sample processing stations: one post (single station ball mills), two position (double work stations mills) and more positionss (multi work station ball mills). Various kinds of different materials can be ground by the mill with dry or wet method. A ball mill grinds material by rotating a cylinder with balls causing the balls to fall back into the cylinder and onto the material to be ground. The cylinder rotates at a relatively slow speed, allowing the balls to cascade through the mill base, thus grinding or dispersing the materials. Milling jars and ball mill medias can be made by different materials such as: tungsten carbide, stainless steel, agate, zirconia, aluminum oxide.