The precision CNC-machined aluminum ball head with black anodized surface treatment has a diameter of 26mm. The middle clamp and knob, made from alloy die-casting, are designed to achieve the tightest grip with the least effort. This product provides an additional mounting option in your car. The base of the ball head is designed to fit standard car cup holders. By turning the central knob, you can adjust the cup holder size to secure it firmly in place. The upper ball head can be paired with universal joints, making it suitable for mounting tablets.