Lifetime Warranty Compatibility: This 20mm ball mount is compatible with RAM Mount B Size Dual Socket Arm Ball and Socket technology allows for nearly unlimited adjustability Mounting size: The ball mount consists of a TPU ball and a 20mm diameter ball head that attaches to a 1/4"-20 external threaded steel post. Universal threaded hole solution for a variety of use cases Anti-slip and anti-vibration: The TPU anti-slip ball head has shock-absorbing and anti-shake functions, and is not easy to loosen. Suitable for any bracket base that supports 20mm ball screw holes, expand the connection of other mobile phone bracket accessories, and can be freely rotated 360° to adjust any angle The ball mount is made of stainless steel, which is durable and not easy to damage. The stainless steel ball head is wrapped with high-quality rubber