Universal Speedball Only is a 1 inch (25mm) ball with combination 1/4-20 and 3/8-16 mounting screws. Push the 3/8-16 outer screw down to reveal the hidden 1/4-20.
Install the ball with the cam-lever in the down position to finger-tight, then lift the lever to add extra locking force to the assembly. The extra force of the cam-lever desig