The screen mesh structure of the Japanese brand Spectrum pro-quality finishing and polishing papers means they don't clog up very fast. You can work with this much longer than with traditional abrasives. It is reversible (yes, you can use both sides!) and washable, enabling faster, more effective finishing and a longer service life. Their synthetic fibre backing contains carefully graded white aluminium oxide abrasive that can be used wet or dry. Lasts longer than the 3M polishing papers. They really give you the most fantastic mirror like finish on fired base metal clay like the BRONZclay and COPPRclay, and of course also on silver clay. They are great on unfired clay, as you simply rinse them clean when they clog up with clay dust. Each sheet is 8 1/2" x 11" or 216x279mm. The set includes 6 sheets, 1 of each of the following sheets: Lime - 4000 grit, 3 Micron, Peach - 3000 grit, 4 Micron, Light Blue - 2000 grit, 9 Micron, Pink - 1000 grit, 15 Micron, Yellow - 800 grit, 18 Micron and Blue - 600 grit, 20 Micron.