CGW Abrasive Flap Disc active grinding agent provides cool cutting. CGW 4 1/2 Regular 27 Depressed center AO flap disc offers high stock removal and extended service life. Disc having an arbor size of 5/8-11 and grit size of 40 is tough and aggressive for a low noise no vibration action. • Grit/Grade: 40 (medium). • Diameter: 4 1/2-inch. • Thickness: Regular. • Backing material: Polyester. • Abrasive material: Blue fired A3 alumina. • Premium blue fired AO grain with a polyester heat treated backing recommended for universal use and provides rapid stock removal and extremely long life. • Contaminate-free for working on flat grinding surfaces most efficient when used between 0°-15° angle the best choice for smooth finishing. • Suitable for: A3 can be used on ferrous metals (alloyed and unalloyed steels high speed steel cast iron) stainless steel non-ferrous metals (aluminum brass copper zinc) as well as on composites plastics and soft and hard woods. • Used with: Right angle grinder/sander. • Sold as 1 Each.