This black 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 3" between the centers of the ball recesses. The kelp green anodized T-Knob makes tightening and loosening the clamp easy, and it can be useful to the cinema industry for color-coding camera rigs.