The mounting system is perfect for high-quality materials that one does not want to damage by drilling: ceramic (tiles), stone, marble, granite, glass, concrete, metal, wood and most plastics*. Unsuitable surfaces, on the other hand, include soft plaster, wallpaper, sheetrock and textiles (such as carpets), which do not provide sufficient firmness and support for surface attachments: There is no adhesion to polyethylene (PE), polypropylene (PP) and polytetrafluoroethylene (PTFE, Teflon). These surfaces are rarely found in tub surrounds or bath enclosures. Although we have described as many examples as possible, our instructions can cover only some of the many surfaces and surface treatments that are suitable. The user is therefore advised to make preliminary tests when considering other types of surface. *For grab bars we only recommend and warranty for use on natural stone, tile, glass, metal and concrete due to ADA requirements and because the surface must be flat, rigid and free of debris, coatings and sealants.