KLINGSPOR's AZ-PLUS combines the superior strength of Alumina Zirconia abrasive grains, the leveling properties of C and D weight paper backing, and a great stearate additive that prevents loading and clogging into one fabulous product. You'll appreciate this combination when sanding bare wood and when sanding sealer coats. Even with the aggressiveness of the grains, AZ-PLUS offers a very consistent finish and will stay sharper longer without loading. The Alumina Zirconia grains work great for dimensioning of wood, the grinding of stainless steel and other hard steels, the sanding of body fillers, and other hard to sand materials. This material is a premium fully resin bonded product.