The carbide rotary bar is a very expensive consumable item because of the material is expensive + hard and hard processing. Cutting surface: Double cut = mesh type for cutting and polishing common steel, forged steel, carbon tool steel, high speed tool steel, alloy tool steel, chrome steel, manganese steel, stainless steel, casting, titanium, nickel, copper/copper alloy. Cutting is sharp and dangerous. Please be sure to wear appropriate protective equipment such as protective glasses. When attaching the rotary bar to the grinder, please ensure that the shaft protrusion (overhang) or less is 0.5 inches (13 mm).