Drive productivity and durability with RADNOR by Norton® Zirconia Alumina Type 27 Flap Discs. Engineered for efficient light stock removal, smooth blending, and refined finishing, these high-quality zirconia discs are built on a dependable fiberglass backing to outlast standard aluminum oxide. Offered in 4", 4 1/2", and 7" sizes and 40, 60, and 80 grit, they accommodate 5/8", 7/8", and 5/8" - 11" arbors for operational versatility.