Application for smooth surfaces]: Our suction cups can be vacuumed on all smooth surfaces such as windows and glass, ceramic tiles. But water can drop them. [Easy to organize]: The thread and the included transparent knurled nut make it easy to organize the space for kitchen accessories and installing DIY furniture or holding decorations, etc. [Dimensions]: Diameter: 40mm, M5 thread height: 10mm. [Quantity]: 8 pieces. [Good Customer Service]: If you have any problem with our suction cups, please feel free to contact us. Specification Details We have compiled a clear analysis table for you about the size and specifications of the M5 suction cup. Our suction cup belongs to M5 nut specification. The specific dimensions are as follows: Suction cup diameter: 40mm M5 nut long: 10 mm Diameter of M5 nuts: 2 mm M5 diameter of the screw cap: 13 mm How to use it? 1. First, you can use it on a smooth, flat surface, and clean the surface with glass cleaner or vinegar before use. 2. Press the