The 3M™ Perfect-It™ Random Orbital Polisher Back-Up Pad helps keep compounding and polishing pads working at peak performance when used with 3M™ Perfect-It™ Random Orbital Polisher. Helping 3M™ Perfect-It™ Random Orbital Compounding and Polishing Pads stay firmly attached to the tool they are designed for use on 3M™ Perfect-It™ Random Orbital Polishers with 15 mm and 21 mm throws.