Cones and plugs are used for deburring, stock removal, grinding, and snagging in hard to reach places. They typically have coarse grits for aggressive removal of material. Common abrasive materials include alumina zirconia, aluminum oxide, and an alumina zirconia/aluminum oxide blend. Cones have a shape number of 16 or 17 depending on shape, with Type 16 having curved sides and a rounded top and Type 17 having a tapered point. Plugs are cylindrical and have a shape type of 18 (square tip) or 18r (round tip). Type 19 is a hybrid combination of cone and plug shapes.