This black, 5" long Ball Clamp with T-Knob from Ultralight Control Systems is used to connect light arms to underwater camera rigs, or arm sections to each other, using 1" mounting balls. This clamp measures 5" between the centers of the ball recesses. The T-knob makes tightening and loosening the clamp easy. The ball recesses on this clamp have cutouts that allow the arm to be placed in virtually any direction. The clamp is made in the USA from Type III anodized aluminum.