Corrosion resistance: Rust and corrosion resistant structures protect against rust. The shower hooks are made of stainless steel, the covers and knobs are made of ABS plastic, and the suction cups are made of high quality rubber. No tools, no drilling, no holes: installation is simple with suction cup technology—just place on a smooth surface, apply pressure, and turn clockwise. Includes adhesive mounting disk: To install the suction cup hook on a rough or uneven surface, use the 3M adhesive mounting disk provided. Scope of application: The suction cup holder is suitable for smooth, non-porous surfaces such as glass, stainless steel, mirrors, and ceramic tiles. For surfaces like wood, matte paint, textured ceramic tile, or frosted glass, use the included adhesive mounting plate. Strong holding capacity: The suction cup is made of high quality silicone material with high stretchability and good airtightness. The 2.7 inch suction cup can hold up to 7.5 pounds.