HEAVY DUTY SUCTION CUP HOOK ~ Set of 3 BLK, each with 22 lb capacity The PRO has excellent strength for the size of the hook with 22 LB of hanging strength. The 2 " round suction cup body attaches to the surface and protrudes 1.15" from the wall. Attachment to natural stones like marble and granite is not recommended since those materials are too porous even though they appear to be non-porous. How do you use this product? View the video and read the instructions for attaching the suction cup to the wall and remember that it will need to be checked and tightened periodically during use. A suction cup does not permanentally fasten to a wall like a nail or screw. Visit Amazon's PRO SUCTION HOOKS store http://www.amazon.com/Pro-Suction-Hooks/pages/default?pageId=TO2MZGLPAL45B35 to see a demo of these strong multi-purpose PRO SUCTION CUP HOOKS that are ideal for home, work and travel so long as a smooth shiny surface is available. Examples are shiny subway or porcelain tiles, glass, mirrors, acrylic glass, Plexiglas, fiberglass, baked enamel appliance panels, powder coated metals like file cabinets and machine tool panels, stainless steel, plastics and dry erase boards. The set includes three black Phthalates-free suction cups for a most secure hold on smooth, non-porous surfaces.