Material: hook using the original German rubber TRU + PU. reusable and more stable than similar products. pu is a relatively soft rubber. can automatically fill within 1mm rough surface. Appearance structure: The appearance of the suction cup hook is made of abs. surface plating material. Long service life. Waterproof. moisture-proof and anti-smoke. Easy to Install:Before installing the suction hook. the surface must be clean and dry. Just lift. push in and lock. No screws. no nails. no glue. no tools required. This suction cup with hooks is easy to organize and store in apartments. school dormitories. and offices. Heavy Duty Suction Cups: Made of high quality ABS plastic and German TUP rubber. the suction cups can withstand a maximum load of 11 lbs. and maintain suction for years. REMOVABLE & REUSABLE:To remove the suction cups for glass. just pull the handle or use a card. pry the bottom of the suction cup. then rinse the suction cup surface under running water to remove dust and residue. suction cup hooks can be reused many times as new. NOTE:The vacuum hooks cannot be used on any porous. uneven. rough or textured surfaces. such as rough coated surfaces. travertine tiles. porous tiles and unpolished marble or wooden door surfaces. etc..