Dico 541-786-21/2 Nyalox Cup Brush 21/2-Inch Blue 240 Grit Nylon bristles impregnated with aluminum oxide Color coded grits: Blue = fine Hex mandrel for quick changing Use with drills Ideal for dried grout removal Can be used on wood, metal or masonry Far safer to use than wire brushes Last up to (10) times longer that Wire Brushes Convenient Shapes and Sizes for all jobs Gray-Extra CoarseOrange-Coarse and Blue-Fine Will not rust & maintains its shape. Safer to use. For light cleaning and polishing of woods and metals