To mount to a circular rail, simple press the plastic "U" clamp around the rail and then connect and tighten the small nut and bolt to close the U clamp. Next connect the diamond plate to the mounted clamp at the required angle and screw in the other bolt through the diamond plate. Now you are ready to connect any of the RAM composite or any other cradle with two holes positioned 1.912" center to center. Placing a rubber lining (not included) between the tube and the mount for a tube with a diameter less than 1" will help the base grab the rail.
High Strength Composite
The "U" in the part number reflects product packaged in poly bag. You cannot rotate the diamond plate on the U clamp when the cradle is connected.