An abrasive sheet is a type of material used for sanding, polishing, and grinding. It is usually made from a combination of materials such as sandpaper, pumice, and other abrasives. Sandpaper is a type of paper with an abrasive material glued to one side, while pumice is a type of volcanic rock that is ground into a powder and used as an abrasive. Both sandpaper and pumice are commonly used in abrasive sheets to provide a rough surface for sanding and grinding.