3M Xtract Paper Disc 216U features a 3M proprietary multi-hole pattern for improved dust extraction in finishing applications. Part of the 3M Xtract Series, designed for optimal dust removal. This innovative multi-hole pattern extracts dust better than 5- or 6-hole products — increasing cut and dramatically increasing disc life. The design does not need to align with the disc pad holes, making switching the discs fast, easy and convenient. Advanced Series Abrasives from 3M are designed to deliver an unbeatable combination of performance and value. Open coat construction and a load-resistant coating further prevent clogging.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. Part of the 3M Xtract Series, designed for optimal dust removal. For maximum dust extraction, use this disc with a 3M Xtract Back-up pad and a random orbital sander with vacuum (both sold separately). We 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.