These quality high density (HD) zirconia flap discs are the big brother to our Premier Grind flap discs. Same excellent quality and value. Multiple layers of zirconia cloth flaps constantly expose new sharp points to the work surface. Laminated by state of the art automated equipment, they have reinforced fiberglass backing that wears with the flaps and will not damage the workpiece. Balance tested to eliminate vibration and provide a smooth cutting, long lasting sanding tool. These flap discs come in 36 Grit, 40 Grit, 60 Grit, and 80 Grit.