DEWALT DW4945 4-1/2-inch rubber backing pad with locking nut is an ideal replacement for your worn out 4-1/2-inch backing pad. The backing pad is a crucial component for attaching sanding discs, foam bonnets, and polishing bonnets. For best results, make sure that you choose a backing pad that properly fits your sander, grinder, or polisher. With a 5/8-x-11-inch locking nut, this steel reinforced rubber backing pad is designed to work at a maximum of 12,000 RPM.