Application for smooth surfaces]: Our suction cups can be vacuumed on all smooth surfaces such as windows and glass, ceramic tiles. But water can let them down. [Easy to organize]: The supplied thread and transparent knurled nut make it easy to organize the space for kitchen accessories and DIY furniture installation or holding decorations, etc. [Dimensions]: diameter: 40 mm, height of the M5 thread: 10 mm. [Quantity]: 8 pieces. [Good customer service]: If you have any problem with our suction cups, please feel co.ukee to contact us. Specification details We have compiled a clear analysis table for you on 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: 40 mm M5 nut long: 10 mm M5 nut diameter: 2 mm M5 diameter of the screw cap: 13 mm How to use it? 1. First of all, you can use it on a smooth flat surface and clean the surface with glass cleaner or vinegar before use. 2.