Bath & Shower Portable Cup Holder

Like any suction cup, it works best with non-porous surfaces. Will not work on porous stone such as travertine. It will last nearly forever on glass, mirror, and smooth tile. However, surfaces like brushed stainless steel, copper, and some plastic shower surrounds, are actually slightly porous. On these slightly porous surfaces, the suction only lasts for a few hours to a day. Plenty long enough to have your drink in the shower, but it will not stay for days like truly non-porous surfaces. This is true for all suction cups, even though ours is the highest quality.