3M™ Disc Pad Face Plate backs a same size fibre disc (sold separately) to provide firm support and the force required for grinding applications. It is used in conjunction with a disc pad hub (sold separately), which attaches to the power tool, and held into place along with the appropriate disc using a retainer nut (sold separately). The 3M™ Disc Pad Face Plate backs a same size fibre disc (sold separately) to provide firm support and the force required for grinding applications. It is used in conjunction with a disc pad hub (sold separately), which attaches to the power tool, and held into place along with the appropriate disc using either a retainer nut (sold separately) or TN or GL quick change attachment systems. This assembly allows the disc pad face plate to be easily changed without removing the disc pad hub, allowing the operator to use a single tool for multiple applications from heavy grinding to finishing a workpiece. Some face plates have ribbing on the bottom face. Ribbed face plates provide additional force when needed for optimal fracturing of the abrasive mineral. By reducing the area of contact, or pressure per square foot (PSI), ribbed face plates increase the grinding pressure of the abrasive with the same amount of operator effort, and extend disc life when dulling is a problem.