Just lift the knurled nut up away from the screw thread to quickly adjust the movable jaw to your workpiece, then push the nut down against the thread and rotate to tighten. Eliminates all that screwing, screwing, screwing.

The thread on the body is only a partial thread, with enough room for the nut to lift up and dis-engage the thread for quick adjustment of the clamp. You then push the nut back down against the thread and rotate it to do the final tightening of the clamp. (Keep a light pressure on the nut into the thread as you tighten.) The thread is asymmetrical with a negative leading angle, which keeps nut locked into the thread.

To assemble, first place the nut in the gap of the jaw. (Apply a tiny dab of grease or oil to the nut threads for smoother operation.) Note that one end of the nut (as shown below) has a small notch that should be facing the tail-end of the clamp. Then slide the jaw onto the clamp body.

Also note that the there is a little spring clip at the tail-end of the clamp that needs to be pressed in as you slide the jaw onto the body. This clip keeps the jaw from sliding back off the body altogether.

Finally, slide the jaw pads onto the business ends of the clamp body and jaw.