Only sticks on smooth, flat surfaces such as glass, mirrors, and tiles. Clean your tiles before mounting the suction cup to ensure a better grip. Rinse the suction cup under running water and let air dry before use. After assembly, leave the product on the wall for 12 hours before using it. This helps the suction cup adhere better. For increased stability, make sure to retighten the screws every 3 months. Each hook holds up to 6 lbs. 9 oz.
The suction cup grips smooth surfaces. http://www.ikea.com/ca/en/images/products/stugvik-hook-with-suction-cup-assorted-colors__0275677_PE413910_S4.JPGSTUGVIK Hook with suction cup, assorted colorshttp://www.ikea.com/ca/en/catalog/products/60288193/602.881.93$10.99/ 4 pack