They don't work.
Wouldn't give it 1 star if I didnt have to. Fell off over and over again even after cleaning the smooth shower walls and trying it with them dry and wet. Fell off after 20 minutes. Box looked previously opened and suction cups were warped and dirty. Guessing these were returned mltpl times. Returned them for my money back. Be careful if you keep them and hope they prevent falls. I would never trust them.
Rating: 1 stars