Designed for Operator Comfort Engineered using urethane foam, 3M™ Stikit™ Center Water Feed Disc Hand Pad is molded in to a bullet shape that is lightweight and easy to grip. The pad has a removable sponge in the center that is designed to be submerged in water. Foam densities range from soft to firm, depending on user preference. Water: The Helpful Agent A key agent in primer and defect sanding, water helps keep the substrate cool and flushes residue off the work piece and abrasive disc, which prevent loading. One reason 3M™ Stikit™ Center Water Feed Disc Hand Pad is a good accessory for these types of applications is because it's considered a "damp sander." In other words, the center sponge dispenses just the right amount of water needed to effectively finish the job. It's less messy than wet sanding, where excessive water is used to flood the surface. The latter typically requires sponging and squeegeeing, too. Having the right accessory readily accessible — like the 3M™ Stikit™ Center Water Feed Disc Hand Pad — makes repairing the surface easy and efficient.