All-in-One Replacement Pad with Bumper! The 1/4 inch pad has 2 layers: The rubber layer provides shock absorption while the foam layer provides the perfect cushion for streak free sanding. No damage to the adjacent surface with the built in bumper! The Trigon Sander Head (Product # W-FCTR180) sits down into the pad while the bumper of the pad rises up around the edge of the sander to protect your walls.