Height adjustment is made by loosening the wingnut and sliding brackets up or down the U-legs.
Tightening the wingnut fixes the height while, at the same time, drawing the channels together for a tight joint. This method is best suited for retrofit installations where an existing surface can serve to suspend the channel sections or in new construction where forming lumber is in place. Mask the grate openings to prevent concrete from entering the channels during placement. Insert anchor lugs into all four corners of each frame. Place and consolidate concrete under and around channels, then finish to proper grade.