Automatic suction cups are designed for different surfaces. For smooth materials like glass or polished marble, standard nitrile rubber (NBR) pads are sufficient. However, for textured or porous surfaces like slate, wood, or patterned tiles, you must select a model with a triple-layered foam rubber seal or a high-flexibility silicone base to prevent air leakage. Ensure the supplier provides a Shore Hardness rating for the rubber; a rating of 50-60 HA is generally ideal for balancing durability and sealing performance.