Designed for use with a random orbital sander, our discs are made of long-lasting aluminum oxide abrasive grains on a light A-weight paper backing suitable for lightweight sanding and finishing. The open coat and load-resistant coating help prevent loading for a longer service life, and make 3M(TM) Stikit(TM) Gold Paper Disc Roll 216U discs well-suited for general sanding and finishing applications on a variety of substrates, including paint, primer, wood, metal, plastic, and composites, including fiberglass. 3M(TM) Stikit(TM) discs are designed to handle a wide range of sanding and finishing needs. These high-quality, coated abrasive products come ready to use with a pressure sensitive adhesive coating on the backside so they conveniently press on to the backup pad, and remove cleanly, leaving an uncontaminated surface for the next disc. A Stikit disc should be used in conjunction with a Stikit backup pad (also called a disc pad and sold separately) that is attached to a random orbital sander. Loading occurs when wood or paint dust clogs the surface of the disc and the abrasive points, which can quickly make the disc ineffective. Open coat construction means the abrasive grains are spaced so that dust and debris can collect in the spaces rather than loading the disc. Additionally, the open coat feature provides a more aggressive cut than a comparable closed coat abrasive of the same grade, for faster results.