The 3M Xtract™ Paper Disc 216U is constructed of aluminum oxide and is suitable for finishing applications on wood as well as primer, paint, sealers, topcoats, fiberglass, and plastics. The 3M™ Hookit™ (hook-and-loop) attachment system makes disc changes fast and easy, meaning the disc can be used again and again for the extent of the abrasive life.For maximum dust extraction, use this disc with a 3M™ Hookit™ Clean Sanding pad and a random orbital sander with vacuum (both sold separately).Sandpaper discs cut better and last longer when dust isn't loading the cutting surface of the abrasives. Our proprietary multi-hole pattern on Clean Sanding products evacuates dust at a higher rate that 5- or 6-hole products. This hole design doesn't even require alignment of holes with the disc pad, making disc changes quick and simple. Open coat construction means the abrasive grains are placed with space between them to help evacuate dust and other sanding debris and avoid clogging the cutting edge of the grains. The load-resistant coating allows the disc to continue cutting even when sanding softwoods, paints, and other materials that would, otherwise, clog the disc and hinder sanding ability. All of this adds up to increased productivity and reduced material consumption.3M chose aluminum oxide abrasive, which is a popular choice among industrial professionals because of its fast cut-rate and long life. This mineral makes a tough, durable abrasive that self-fractures to expose fresh cutting edges in use, whereas traditional abrasives such as garnet quickly wear down with use. Due to their fast cut-rate, hardness, and strength, they are widely used in sanding and finishing applications. Aluminum oxide is suitable for a wide variety of materials in both woodworking and metalworking, including ferrous alloys.