Material: 40pcs 40mm suction cups are made of PVC material, which is very soft, durable, non-yellowing, aging resistant and not easy to fall off, which can meet your various hanging needs. Wide range of uses: Can be used on smooth and clean surfaces such as tiles, stainless steel, painted metal surfaces, transparent glass, etc. Installation method: Wipe the wall with a clean soft cloth. Wash and dry the suction cup before use, stick the hook surface to the wall, press hard on the center of the suction cup and rub the surrounding area to expel the air. Note: Do not hang valuables on this hook.