Review on Suction Cup Hooks: Quntis 4PCS Heavy Duty Large Clear Shower Hooks - Ideal for Hanging Towels, Bathrobes, Loofahs, and More - Easy to Install! by Kelly Thompson

These are amazing quality and adhere perfectly to the shower tiles! Very satisfied. UPDATE 12/13/2018: I bought a large stained glass window and wanted to hang it on our sliding glass door, but since they are metal doors I didn't know how. Qunti's hook to the rescue! The stained glass window is very heavy but has been hanging on the glass for several weeks thanks to the Quntis hook - it hasn't moved a millimeter. Even opening and closing the door multiple times keeps the heavy stained glass panel firmly in place. These hooks are amazing!