Suction cup design: The spiral suction cup has an arched design. The vacuum suction cup has superior adhesion and adheres firmly to smooth surfaces without you having to worry about items falling. Excellent adhesion: The spiral suction cup has strong adhesion and adheres firmly to various smooth surfaces. For example, you can attach the spiral suction cup to glass, marble and tile surfaces. Ideal for temporarily hanging items. Knurled nut included: A knurled nut is included in the product packaging. This is an accessory that attaches to the top of the suction cup. The main function of the knurled nut is to facilitate hanging items on the suction cup. Simply tighten the nut and the suction cup. Durable PVC material: The glass suction cup is made of PVC plastic. Suction cups made of this high-quality material are reliable and durable. The glass suction cup is soft and durable, and does not easily come loose or deform. Easy installation and removal: The screw-on suction cup is easy to install. You do not need to drill holes, tighten screws or use glue. To install, first wipe the contact surface clean with a towel or cloth, then press it firmly onto the smooth surface to squeeze all the air out of the suction cup.