CGW Abrasive Flap Disc is made of excellent carbon and stainless steel. CGW 27 4 1/2 XL Depressed center ZA flap disc offers high stock removal and extended service life. Disc having an arbor size of 7/8 and grit size of 40 is tough and aggressive for a low noise no vibration action. • Diameter: 4 1/2-inch. • Thickness: XL. • Backing material: Polyester/Cotton. • Abrasive material: Z3 -100% zirconia alumina. • Grit/Grade: 40 (medium). • Active grinding agent provides cool cutting with light pressure special optimized resin bond offers maximum cutting capacity strong edge stability and long life. • Premium zirconia alumina grain with a poly/cotton heat-treated backing. The poly/cotton combination provides low stretch and strength for the high zirconia concentration that Z3 contains and enables fast grain removal for carbon based steels (26% more than the competition) offering excellent life. • Applications: Deburring deflashing rust removal snagging; Used with right angle grinder/sander; Applicable materials: Ferrous and non-ferrous metals stainless steel high tensile alloys woods plastics. • Contamination-free; Used on flat grinding surfaces most efficient when used between 0°- 15°angle the best choice for smooth finishing. • Made in USA. • Sold as 1 Each.