When converting Milwaukee Sander Grinders to sanding operations a variety of sanding disc backing pad systems are available. The Rubber Backing Pad is more durable than the Phenolic and but is also heavier in weight. Where heavy production sanding will be encountered, this is a more viable option. When using the 9 inch Rubber Backing Pad 49-36-3750 use disc nut 49-40-0360. Does not include sanding disc. Order separately.