The dial inside the clamp frame with the 1/4" thread, and to which the 5/8" stud is attached, rotates freely with nothing connected to it. Whatever one screws onto it -- in this case the 5/8" stud -- needs to screw all the way onto the 1/4" threaded post and create enough friction with the 1/4" thread's base plate to prevent rotation. I assume the 5/8" stud is secured so it doesn't rotate, otherwise the clamp wouldn't be terribly functional.