Kit includes ceramic grit of 80, 120, 220 and Trizact micron 35, 20, 10, 5; 3 of each grade. Full set of purple ceramic and trizact abrasives. Excellent multi-purpose abrasive. Ceramic cubitron material is self-sharpening. Its long life and uniform cutting action are the best in the industry. The purple color is a trademark of 3M. Woodworking: great for regrinding tool edges that have been damaged or rounded over: chisels, woodturning tools, counter-sinks, drill bits, etc. Its aggressive bite and non-loading properties are ideal for sanding wood as well as for use on various non-ferrous and tool steels. Jewelry: Jewelers also prefer this material for its performance on precious metals, including grinding sprues off of raw castings. The best honing abrasives on the market. Produced with 3M's new microreplication technology, the micropyramids deliver fast, consistent cutting action through their long life. Woodworking: perfect for high-speed steels, it allows sharpening of a wide array of woodcarving and turning tools and knives. Fine hone and maintain the tips & edges of flat chisels, drill bits, counter sinks, fluted end mills, etc. Jewelry: fantastic results on jewelry: performs better than emery paper and fills porosity. Also works great on plastics and for glass defect repair. Disc size: 3" diameter.