Industrial quality: Corundum with resin bonding agent. For sanding soft and hard woods, chip board, fibre plates, non-ferrous metals, steel, plastics, cork, rubber and minerals. Self adhesive. Available in 80, 150 or 240grit. Available are self adhesive Waterproof Sanding Discs 320grit (dia. 250 mm). Aluminium oxide with resin bonding agent. For sanding non-ferrous metals, steel, glass, PC cards, plastics and ceramics. May be used with the coolant system.