Description: The measurement is not to describe the length of the entire adapter, while measure the diameter of the ball from top of one end to another. The Dual Ball Mount Arm is made of a sturdy composite material, ball joints are coated in a rubber material, the middle is connected by stainless steel. Compatible with all industry standard Garmin and GPS device. Compatible for RAM, for mohile phone brackets. With the dual ball adjustments, this mount allows you to have the flexibility of rotating your device 360 degrees. Specification: Product Size: 25mm to 25mm: 63x25mm/2.48x0.98inch 25mm to 17mm: 52.5x25mm/2.07x0.98inch 25mm to 15mm: 50.5x25mm/1.99x0.98inch Material: stainless steel rubber Package Includes: 1 Piece Composite Ball Adapter Note: 1. Please allow slightly error due to manual measurement. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. 3. Wish you a wonderful on-line shopping!