Pressure Sensitive Adhesive (PSA) sanding discs are designed for lighter duty blending, medium stock removal, finishing, and polishing. Adhesive allows for convenient mounting and easy removal. Discs can be mounted to a backing pad or directly to a steel platen depending on the tool being used and the desired effect. Backing pads add cushioning to allow some flexibility for working a surface. Discs can have a cloth, film, or paper backing. They may be solid or contain vacuum holes for dust removal. Common abrasive materials include aluminum oxide, alumina zirconia, silicon carbide, ceramic, and diamond. Choose from very coarse to ultrafine grade, or corresponding grit, depending on material being worked and level of precision required. Some paper- and film-backed discs are available as a continuous disc roll.