Ball with 2,5 cm diameter with Whitworth thread made of anticorodal aluminum and anodized with 40 microns (military standard) to ensure the maximum durability and excellent resistance to wear and to sea salt. This ball is designed to be mounted on all accessories, both photo and video (for example Go Pro, compact digital cameras, DSLR…) that are arranged with thread Whitworth. This special ball allows to couple the above accessories to all Carbonarm systems such as polecams, arms, clips, etc. .. An o-ring at the center of the ball is acts like a clutch: the ball tightened by the clamp can be loosened so as to move the arm in the water without having to re-tighten it. On the ball a hexagonal hole is provided to tighten it by allen key.