For additional framing support between panel points, 1 1/2” x 3″ tubing can be inserted above Cross Tubes and secured with Cross Tube Clips. Self-tapping sheet metal screws are provided with clips.
Cross Tube Clips for 1½″ x 3″ Tube Framing Support - Chicago Clamp
Home Systems Tube Framing Clamp Systems Joist Grip Tube Framing Clamp System Cross Tube Clips