These 4" FLAT-TOP ABRASIVES come already mounted on their respective FLAT TOP discs. For crisper, flatter grinding, choose the option WITHOUT Cushion Pads. For a smoother, quieter, and longer-lasting grinding, choose the option WITH Cushion Pads. Available in 4" Diameter only: Set of 3 grades or individual grades.Available WITH or WITHOUT Cushion Pads. No setup required; start using them right away. NEED REPLACEMENTS? Get them here: > This is an excellent multi-purpose grinding and sanding abrasive. 3Mâ„¢ Ceramic Cubitron IIâ„¢ material is self-sharpening. Its long life & uniform cutting action are the best in the industry. JEWELRY applications: Great for grinding sprues from raw castings, shaping the shank of a ring. Quickly takes down excess solder on silver, gold, platinum, etc. WOODWORKING applications: Awesome sharpening abrasive. Regrinds tool edges that have been damaged or rounded over: chisels, woodturning tools, counter-sinks, drill bits, etc. Its aggressive bite & non-loading properties are ideal for sanding wood as well as for use on various non-ferrous & tool steels. AUTOMOTIVE applications: Perfect for shaping metal, deburring tubing, and any custom metal fabrication.