Description: Made of rubber and stainless steel, windproof, durable and anti-rust. Rough surface, 25mm ball head diameter, increase the friction of the contact area, non-slip and shock-proof. Precision machining screw made of stainless steel. The nut can be adjusted according to the depth of the screw hole, and the ball head is firmly fixed. Easy to install, 1.25mm pitch, M8 / M10 suitable for rearview mirror or phone holder. Size Chart: M8 Size: Ball Head Diameter: approx. 25mm / 0.98 inch Thread Length: approx. 11mm / 0.43 inch Pitch: approx. 1.25mm / 0.05 inch Bottom Diameter: approx. 8mm / 0.31 inch Total Length: approx. 52mm / 2.05 inch M10 Size: Ball Head Diameter: approx. 25mm / 0.98 inch Thread Length: approx. 11mm / 0.43 inch Pitch: approx. 1.25mm / 0.05 inch Bottom Diameter: approx. 10mm / 0.39 inch Total Length: approx. 52mm / 2.05 inch Package Includes: 1 Piece Motorcycle Mounts 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. Thank you! 3. Wish you a wonderful on-line shopping!